refactor: remove Pinia state management and IndexedDB storage

Remove all client-side state management and data caching as the
application no longer needs to manage data analysis features.

Changes:
- Remove Pinia store system (app/stores/ directory)
  - metadata.ts: Store for table metadata
  - tableDataFactory.ts: Factory for creating table data stores
  - README.md: Comprehensive store documentation
- Remove IndexedDB storage utility (app/utils/storage.ts)
- Remove Pinia dependencies from package.json
  - @pinia/nuxt
  - pinia
- Remove Pinia module from nuxt.config.ts
- Remove vendor-pinia chunk configuration
- Remove server services (server/services/ directory)
  - table-service.ts: Supabase-dependent table operations
  - query-parser.ts: Query parsing utilities
  - query-runner.ts: Query execution utilities

The application now operates as a stateless authentication portal
without client-side data caching or state management.

nuxt4-app/package.json

@@ -13,10 +13,8 @@
     "@nuxt/image": "^1.11.0",
     "@nuxt/test-utils": "^3.19.2",
     "@nuxt/ui": "^4.0.0",
-    "@pinia/nuxt": "^0.11.2",
     "@vite-pwa/nuxt": "^0.9.1",
     "nuxt": "^4.1.2",
-    "pinia": "^3.0.3",
     "typescript": "^5.9.2",
     "vue": "^3.5.22",
     "vue-router": "^4.5.1"