feat: add version management with setuptools-scm

- Configure hatch-vcs for automatic version generation from git tags
- Update pyproject.toml to use dynamic versioning
- Add src/_version.py for runtime version access
- Update src/__init__.py to import version from _version
- Add __APP_VERSION__ to frontend vite config
- Add version script to frontend package.json
- Update CI workflows to trigger on version tags instead of branches

frontend/src/vite-env.d.ts

@@ -1 +1,3 @@
 /// <reference types="vite/client" />
+
+declare const __APP_VERSION__: string