feat(debug): enable Python debug workflow and debug server integration

Adds an end-to-end Python debug workflow for the extension.
Includes a new prepare-debug.ps1 script and a VS Code task.
Extends the Python server and extension to coordinate a debug session and safe startup.

- Add prepare-debug.ps1 and a VS Code task to build the debug bundle
- Enable Python debug wiring in the server and tests
- Ensure a single stable Python debug session during startup

package.json

@@ -124,6 +124,7 @@
   },
   "scripts": {
     "compile": "node esbuild.js --production",
+    "compile:debug": "node esbuild.js",
     "watch": "node esbuild.js --watch",
     "package": "node esbuild.js --production"
   },