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>

assets/logos/live-tv.svg

@@ -0,0 +1,21 @@
+<!-- Original Luma Live TV artwork, MIT. Shares the browser icon's blue/cyan material. -->
+<svg xmlns="http://www.w3.org/2000/svg" width="128" height="128" viewBox="0 0 128 128">
+  <defs>
+    <linearGradient id="rim" x1="29" y1="23" x2="94" y2="107" gradientUnits="userSpaceOnUse">
+      <stop stop-color="#c1f7ff"/>
+      <stop offset="1" stop-color="#6985ed"/>
+    </linearGradient>
+    <linearGradient id="screen" x1="29" y1="27" x2="96" y2="86" gradientUnits="userSpaceOnUse">
+      <stop stop-color="#78e5fa"/>
+      <stop offset=".42" stop-color="#3299ed"/>
+      <stop offset="1" stop-color="#5143d4"/>
+    </linearGradient>
+  </defs>
+  <ellipse cx="64" cy="111" rx="33" ry="4" fill="#000" fill-opacity=".16"/>
+  <rect x="58" y="86" width="12" height="19" rx="4" fill="url(#rim)"/>
+  <rect x="43" y="103" width="42" height="6" rx="3" fill="url(#rim)"/>
+  <rect x="14" y="23" width="100" height="68" rx="14" fill="url(#rim)"/>
+  <rect x="18" y="27" width="92" height="60" rx="10" fill="url(#screen)"/>
+  <path d="M54 43.5c0-2.2 2.4-3.6 4.3-2.5l24 13.5a2.9 2.9 0 0 1 0 5l-24 13.5c-1.9 1.1-4.3-.3-4.3-2.5z" fill="#fff"/>
+  <circle cx="99" cy="38" r="3" fill="#ff6580"/>
+</svg>