feat: modernize UI with Astro+Svelte and optimize Docker build

- Migrated frontend to Astro + Svelte 5 for cyberpunk aesthetic
- Switched to Bun for faster frontend builds
- Implemented multi-stage Docker build for smaller image size
- Refactored backend to serve static assets and proxy API requests
- Added recovery mode for manual file management

ui/.gitignore

@@ -0,0 +1,24 @@
+# build output
+dist/
+# generated types
+.astro/
+
+# dependencies
+node_modules/
+
+# logs
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+
+
+# environment variables
+.env
+.env.production
+
+# macOS-specific files
+.DS_Store
+
+# jetbrains setting folder
+.idea/