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/package.json

@@ -9,13 +9,15 @@
   },
   "scripts": {
     "build": "node esbuild.mjs",
-    "watch": "node esbuild.mjs --watch"
+    "watch": "node esbuild.mjs --watch",
+    "typecheck": "tsc --noEmit"
   },
   "keywords": [],
   "author": "",
   "license": "ISC",
   "devDependencies": {
-    "esbuild": "^0.27.4"
+    "esbuild": "^0.27.4",
+    "typescript": "^5.9.3"
   },
   "dependencies": {
     "chart.js": "^4.5.1",