feat: Migrate exercise to issue-based flow

.coveragerc

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+[run]
+relative_files = True

.devcontainer/devcontainer.json

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+{
+  "name": "Python 3",
+  "image": "mcr.microsoft.com/vscode/devcontainers/python:3.13",
+  "postCreateCommand": "pip install -r requirements.txt&& pip install pytest coverage pytest-cov",
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-python.python",
+        "ms-python.debugpy",
+        "github.vscode-github-actions"
+      ]
+    }
+  }
+}

.github/steps/1-step.md

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+## Step 1: Continuous Integration
+
+GitHub Actions is a great way to automate several of your recurring tasks, saving you time to work on the more challenging and fun problems!
+
+One of the most common tasks a developer deals with is testing their code. Unfortunately, this is often tedious and things get skipped or simply overlooked. Even more so, we often need to test against many frameworks, operating systems, and other situations, exaggerating the problem.
+
+Let's learn how to automate this ever-growing need for testing our code by using workflows in GitHub Actions.
+
+### What is Continuous Integration?
+
+[Continuous integration](https://en.wikipedia.org/wiki/Continuous_integration) can help you stick to your team’s quality standards by running tests and reporting the results on GitHub. CI tools run builds and tests, triggered by commits. The quality results post back to GitHub in the pull request. The goal is fewer issues in `main` and faster feedback as you work.
+
+### ⌨️ Activity: Start our sample Python application
+
+1. Use the below button to open the **Create Codespace** page in a new tab. Use the default configuration.
+
+   [![Open in GitHub Codespaces](https://github.com/codespaces/badge.svg)](https://codespaces.new/{{full_repo_name}}?quickstart=1)
+
+1. Confirm the **Repository** field is your copy of the exercise, not the original, then click the green **Create Codespace** button.
+
+   - ✅ Your copy: `/{{full_repo_name}}`
+   - ❌ Original: `/skills/test-with-actions`
+
+1. Wait a moment for Visual Studio Code to load in your browser.
+
+1. In the left navigation, select the **Explorer** tab to show the project files.
+
+1. Open the `src/calculations.py` and `tests/calculation_tests.py` files.
+
+1. Take a moment to read these files to become familiar.
+
+1. Expand VS Code's built-in terminal panel.
+
+   > 💡 **Tip**: The keyboard shortcut is `CTRL` + `J`.
+
+1. Run the below command to install the required Python libraries and tools to show code coverage.
+
+   ```bash
+   pip install -r requirements.txt
+   pip install pytest coverage pytest-cov
+   ```
+
+1. Run the below command to run all unit tests and view coverage information.
+
+   ```bash
+   pytest --cov=src --verbose
+   ```
+
+1. Add a comment to let Mona know the results of your coverage report. After reviewing, she will provide the next steps.
+
+   ```md
+   @professortocat, I've run my coverage report.
+   Seems there is some opportunity to increase the test coverage. 🧐
+   What should we do next?
+   ```

.github/steps/2-step.md

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+## Step 2: Workflow files
+
+The best way to add automation to your project's repository is with a GitHub Actions Workflow. Let's look at the anatomy of a workflow then create 2 of them.
+
+### What are the parts of workflow?
+
+![An illustration with a left half and a right half. On the left: illustration of how GitHub Actions terms are encapsulated. At the highest level: workflows and event triggers. Inside workflows: jobs and definition of the build environment. Inside jobs: steps. Inside steps: a call to an action. On the right: the evaluated sequence: workflow, job, step, action.](https://user-images.githubusercontent.com/6351798/88589835-f5ce0900-d016-11ea-8c8a-0e7d7907c713.png)
+
+- **Workflow**: A unit of automation from start to finish. It begins when the trigger (`on`) matches an activity in the repository. It consists of 1 or more jobs.
+
+- **Jobs**: The workflow's jobs each run in their own isolated environments and can be configured differently. They run in parallel unless configured otherwise or dependencies are set.
+
+- **Steps**: The steps area is a series of related actions that achieve a job's goal. A step can be a pre-made _Action_ from the Actions Marketplace, a private Action, a local custom script, or even direct code.
+
+- **Action**: Each step is an _Action_, a piece of automation written in a way that is compatible with workflows. Actions can be written by GitHub, by the open source community, or specific to the project.
+
+In the above `Example Workflow` file, it will start when any commits are pushed to the repository on any branch. It will run 1 job with the name `build`. That job's first step uses a pre-made _Action_ from the `actions` organization named `checkout` that clones the code from the repository into the job's environment.
+
+You can explore all of the configuration options in the [GitHub Actions Docs](https://docs.github.com/actions/using-workflows/workflow-syntax-for-github-actions).
+
+### ⌨️ Activity: Add a workflow to run tests
+
+1. Open a web browser tab and navigate to this exercise repository. The Codespace is not needed right now.
+
+1. In the top navigation, select the **Actions** tab.
+
+1. In the left navigation, above list of workflows, click the **New workflow** button.
+
+   <img width="250" alt="image" src="https://github.com/user-attachments/assets/babb2cec-dc4c-42a2-a28c-69da8e9ea79d" />
+
+1. Enter `python` into the search box and click the **Enter** button.
+
+   <img width="300" alt="search box with 'python' value" src="https://github.com/user-attachments/assets/34f2795c-85e8-4dc8-b03b-eac73e70e309" />
+
+1. Find the **Python package** workflow and click the **Configure** button to open a file editor with a pre-made workflow.
+
+   <img width="250" alt="image" src="https://github.com/user-attachments/assets/4a2ff616-aedd-41b5-a24c-82014e98bbee" />
+
+1. Around line 6, simplify the `on` trigger. Remove the `push` trigger and keep the `pull_request` trigger.
+
+   ```yml
+   on:
+     pull_request:
+       branches: ["main"]
+   ```
+
+1. Around line 38, change the command to show more details in the logs.
+
+   ```yml
+   - name: Test with pytest
+     run: |
+       pytest --verbose
+   ```
+
+1. Above the editor, on the right, click the **Commit changes...** button. Commit directly to the `main` branch.
+
+<details>
+<summary>Having trouble? 🤷‍♂️</summary>
+
+Indention of `.yml` files is important. If you are getting syntax errors, that may be the reason.
+
+Finished workflow file: `.github/workflows/python-package.yml.example`
+
+<details>
+
+### ⌨️ Activity: Add a workflow to show test coverage
+
+1. Switch to the VS Code Codespace.
+
+1. Check the status bar for a pending update. Click it to pull your recently committed workflow.
+
+   <img width="130" alt="image" src="https://github.com/user-attachments/assets/c3eb17cf-a18e-4fae-bf18-cda900c7c6d3" />
+
+1. In the left navigation, select the **Explorer** tab to show the project files.
+
+1. Expand the `.github/workflows/` folder.
+
+1. Add a new file with the following name and open it.
+
+   ```txt
+   python-coverage.yml
+   ```
+
+1. Enter the name and set it to trigger on pull requests targeting the `main` branch.
+
+   ```yml
+   name: Python Coverage
+
+   on:
+     pull_request:
+       branches:
+         - main
+
+   permissions:
+     pull-requests: write
+   ```
+
+1. Add the `python-coverage` job and a first step that gets the repository content.
+
+   ```yml
+   jobs:
+     python-coverage:
+       runs-on: ubuntu-latest
+
+       steps:
+         - name: Checkout code
+           uses: actions/checkout@v4
+   ```
+
+1. Add steps to install Python and required packages.
+
+   ```yml
+   - name: Set up Python
+     uses: actions/setup-python@v4
+     with:
+       python-version: 3.13
+
+   - name: Install dependencies
+     run: |
+       pip install -r requirements.txt
+       pip install pytest==8.4.1
+       pip install coverage==7.9
+       pip install pytest-cov==6.2.1
+   ```
+
+1. Add steps to run the coverage report on the `src` folder.
+
+   ```yml
+   - name: Run tests and generate coverage details
+     run: pytest --cov=src
+   ```
+
+1. Add a final step that uses a pre-made GitHub Action to share the coverage report as a comment on the pull request.
+
+   {% raw %}
+
+   ```yml
+   - name: Coverage comment
+     uses: py-cov-action/python-coverage-comment-action@v3
+     with:
+       GITHUB_TOKEN: ${{ github.token }}
+       MINIMUM_GREEN: 90
+       MINIMUM_ORANGE: 70
+
+   - name: Fail if below threshold
+     run: coverage report --fail-under=90
+   ```
+
+   {% endraw %}
+
+1. Commit and push the changes to your `python-coverage.yml` file to the `main` branch.
+
+> [!TIP]
+> Dis you notice the `uses:` statements? Those are pre-made steps from the free [Actions Marketplace](https://github.com/marketplace?type=actions). Consider trying one of them out before you create your own custom scripts (to maintain)! There are lots of AWESOME creations from the community!
+
+1. With both new workflows pushed to GitHub, Mona will review your work and post the next steps.
+
+<details>
+<summary>Having trouble? 🤷‍♂️</summary>
+
+Indention of `.yml` files is important. If you are getting syntax errors, that may be the reason.
+
+Finished workflow file: `.github/workflows/python-coverage.yml.example`
+
+<details>