chore: unify version to 9.7.0 with single source of truth

- Add VERSION file at project root as canonical version source
- Sync all version references: package.json, pyproject.toml, config.py,
  Chart.yaml, docs/CONFIGURATION.md (all were out of sync: 9.0.1, v9.6, 0.1.0)
- Replace hardcoded v9.6 in SettingsPage and About page with dynamic
  APP_VERSION import from @/lib/version.ts
- Add Vite define for __APP_VERSION__ reading from package.json at build time
- Add TypeScript global declaration for __APP_VERSION__

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/vite.config.ts

@@ -5,8 +5,14 @@ import { sri } from 'vite-plugin-sri3'
 import path from 'path'
 import fs from 'fs'
 
+// Read version from package.json for global define
+const pkg = JSON.parse(fs.readFileSync(path.resolve(__dirname, 'package.json'), 'utf-8'))
+
 // https://vite.dev/config/
 export default defineConfig({
+  define: {
+    __APP_VERSION__: JSON.stringify(pkg.version),
+  },
   plugins: [
     TanStackRouterVite({ target: 'react', autoCodeSplitting: true }),
     react(),