Initial scaffold: Beat Pocket MV3 extension

- manifest.json with MV3 config, host permissions for beat-battle.net
- content/detector.ts: route + overlay observer, emits bbp:phase events
- content/layout.ts: defensive mobile-first layout reflow
- content/chat-drawer.ts: bottom-sheet drawer, dispatches synthetic events
  through site's own React-managed textarea + button (preserves auth,
  rate-limit, mute, profanity guards)
- content/util/selectors.ts: text- and role-based fallback chain
- content/util/ws-proxy.ts: lightweight WebSocket instrumentation, no
  payload capture
- content/inject.css: mobile overrides using site's existing --bb-* vars
- background.js: MV3 service worker stub
- package.json + tsconfig.json + esbuild.config.mjs: build pipeline
- icons/: 16/32/48/128 placeholder PNGs (chili-red disc)
- docs/PLAN.md: full V1 architecture, risks, scope
- README.md: scope, dev workflow (load unpacked), tech

tsconfig.json

@@ -0,0 +1,20 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "ES2020",
+    "moduleResolution": "Bundler",
+    "lib": ["ES2020", "DOM", "DOM.Iterable"],
+    "strict": true,
+    "noImplicitAny": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "isolatedModules": true,
+    "noEmit": true,
+    "types": ["chrome"]
+  },
+  "include": ["extension/**/*.ts"],
+  "exclude": ["dist", "node_modules"]
+}