feat: Add Markdown View Plugin with React and Chakra UI

- Implemented main application structure with App and View components.
- Integrated React Markdown for rendering Markdown content.
- Added API function to fetch Markdown content from the backend.
- Created a custom Chakra UI theme to align with Airflow's design.
- Configured Vite for building the application with appropriate asset paths.
- Included a sample Markdown file for initial content display.
- Set up TypeScript configuration for better development experience.

markdown_view_plugin/README.md

@@ -0,0 +1,76 @@
+
+## Building the Plugin
+
+You can build the plugin into a wheel file using any PEP-517 compatible build frontend. The build process will automatically:
+
+1. Install UI dependencies using pnpm
+2. Build the React frontend
+3. Package everything into a wheel file
+
+This is handled by a custom Hatch build hook (`hatch_build.py`).
+
+### Example build commands
+
+```bash
+# Using uv (recommended)
+uv build
+
+# Or using pip
+pip wheel .
+
+# Or using hatch directly
+hatch build
+```
+
+The build process will fail if `pnpm` is not installed or if the UI build fails.
+
+## Quick Test Checklist
+
+After building, you can quickly verify that the UI static files are included in the wheel:
+
+```bash
+# one-liner smoke test
+rm -rf ui/dist && uv build
+unzip -l dist/airflow_markdown_view_plugin-*.whl | grep 'ui/dist/index.*.js'
+```
+
+If the grep shows your JS bundles, you’re golden. If not, the hook didn’t run—fix it before shipping.
+
+# Markdown View Airflow Plugin
+
+This plugin allows users to render Markdown content from a `view.md` file directly within the Airflow UI.
+
+## Features
+
+*   Displays content from a `markdown_view_plugin/view.md` file.
+*   Uses FastAPI for the backend and React/Vite for the frontend.
+*   Integrates with Airflow's UI theme, including light/dark mode support.
+*   Provides a theme toggle button within the plugin's view.
+
+## Setup
+
+1.  **Place the Plugin:** Put the entire `markdown_view_plugin` directory into your Airflow `plugins` folder.
+2.  **Install UI Dependencies:** Navigate to the `markdown_view_plugin/ui` directory and run:
+    ```bash
+    pnpm install
+    ```
+3.  **Build the UI:** After installing dependencies, build the React frontend:
+    ```bash
+    pnpm run build
+    ```
+    This will create a `dist` folder inside `markdown_view_plugin/ui`.
+4.  **Restart Airflow Webserver:** After adding the plugin and building the UI, restart your Airflow webserver and scheduler.
+5.  **Access the Plugin:** In the Airflow UI, navigate to the "Plugins" menu. You should find a link to the "Markdown View" (the exact name and category might depend on future menu link configuration in `markdown_view_plugin.py`). Clicking this link will take you to the plugin's page.
+
+## Customization
+
+*   To change the displayed content, edit the `markdown_view_plugin/view.md` file.
+*   The UI can be further customized by modifying the React components in `markdown_view_plugin/ui/src/`.
+*   The backend logic is in `markdown_view_plugin/markdown_view_plugin.py`.
+
+## Development
+
+*   **Backend:** The FastAPI application is defined in `markdown_view_plugin.py`.
+*   **Frontend:** The React/Vite application is in the `markdown_view_plugin/ui/` directory.
+    *   To run the frontend in development mode (with hot reloading), navigate to `markdown_view_plugin/ui` and run `pnpm run dev`.
+    *   Ensure your `vite.config.ts` has the correct `base` path and any necessary proxy configurations if you are developing against a running Airflow instance.