Migrate frontend from JavaScript to TypeScript

- Rename all 54 .js files to .ts, update esbuild entry point
- Add tsconfig.json, TypeScript devDependency, typecheck script
- Create types.ts with 25+ interfaces matching backend Pydantic schemas
  (Device, OutputTarget, ColorStripSource, PatternTemplate, ValueSource,
  AudioSource, PictureSource, ScenePreset, SyncClock, Automation, etc.)
- Make DataCache generic (DataCache<T>) with typed state instances
- Type all state variables in state.ts with proper entity types
- Type all create*Card functions with proper entity interfaces
- Type all function parameters and return types across all 54 files
- Type core component constructors (CardSection, IconSelect, EntitySelect,
  FilterList, TagInput, TreeNav, Modal) with exported option interfaces
- Add comprehensive global.d.ts for window function declarations
- Type fetchWithAuth with FetchAuthOpts interface
- Remove all (window as any) casts in favor of global.d.ts declarations
- Zero tsc errors, esbuild bundle unchanged

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

server/tsconfig.json

@@ -0,0 +1,19 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "strict": false,
+    "noEmit": true,
+    "skipLibCheck": true,
+    "esModuleInterop": true,
+    "allowImportingTsExtensions": true,
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "lib": ["ES2020", "DOM", "DOM.Iterable"],
+    "baseUrl": "src/wled_controller/static",
+    "rootDir": "src/wled_controller/static"
+  },
+  "include": ["src/wled_controller/static/js/**/*.ts"],
+  "exclude": ["node_modules", "src/wled_controller/static/dist"]
+}