Merge Luma launcher fork into monorepo

Move trampoline files (boot-hook, watcher, overlay) into trampoline/
subdirectory. Add upstream Luma v2.3.1 source at repo root with our
additions:

- Page::Ha (4th nav tab) with placeholder empty state
- HA tab config schema and default entity mapping (ha-home/)
- Nav keys renamed: "home" → "start", new "ha" tab between Apps and Settings
- All state.rs/view.rs/main.rs/tests.rs updated for 4-tab navigation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

trampoline/overlay/appinfo.json

@@ -0,0 +1,24 @@
+{
+  "id": "com.webos.app.home",
+  "version": "1.0.0",
+  "vendor": "LG Electronics",
+  "type": "web",
+  "main": "index.html",
+  "title": "Home",
+  "transparent": true,
+  "noSplashOnLaunch": true,
+  "icon": "icon.png",
+  "mediumIcon": "icon.png",
+  "largeIcon": "icon.png",
+  "iconColor": "#1ec15f",
+  "visible": false,
+  "disableBackHistoryAPI": true,
+  "lockable": false,
+  "hasPromotion": false,
+  "accessibility": {
+    "supportsAudioGuidance": true
+  },
+  "defaultWindowType": "home",
+  "handleScreenRemoteKey": true,
+  "bgColor": "#000000"
+}