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/index.html

@@ -0,0 +1,22 @@
+<!doctype html>
+<html><head><meta charset="utf-8"><title>Home</title>
+<meta name="viewport" content="width=1920">
+<style>html,body{margin:0;padding:0;width:1920px;height:1080px;background:transparent;overflow:hidden}</style>
+<script>
+(function(){
+  try {
+    var b = new WebOSServiceBridge();
+    b.onservicecallback = function(){};
+    b.call('luna://com.webos.applicationManager/launch', JSON.stringify({id:'com.ecklf.luma'}));
+  } catch(e) {
+    setTimeout(function(){
+      try {
+        var b2 = new WebOSServiceBridge();
+        b2.onservicecallback = function(){};
+        b2.call('luna://com.webos.applicationManager/launch', JSON.stringify({id:'com.ecklf.luma'}));
+      } catch(e2){}
+    }, 500);
+  }
+})();
+</script>
+</head><body></body></html>