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>

tools/release-gate.mjs

@@ -0,0 +1,60 @@
+function versionParts(version) {
+  if (typeof version !== 'string' || !/^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)$/.test(version)) {
+    throw new Error(`Invalid numeric release version: ${version}`);
+  }
+  return version.split('.').map(BigInt);
+}
+
+export function isVersionIncrease(previous, current) {
+  const before = versionParts(previous);
+  const after = versionParts(current);
+  for (let index = 0; index < before.length; index++) {
+    if (before[index] !== after[index]) return after[index] > before[index];
+  }
+  return false;
+}
+
+export async function isReleaseMerge({ github, context }) {
+  if (
+    context.eventName !== 'push' ||
+    context.ref !== 'refs/heads/main' ||
+    context.payload.deleted ||
+    context.payload.forced ||
+    !context.payload.before ||
+    /^0+$/.test(context.payload.before)
+  ) {
+    return false;
+  }
+
+  const repository = `${context.repo.owner}/${context.repo.repo}`;
+  const pulls = await github.paginate(github.rest.repos.listPullRequestsAssociatedWithCommit, {
+    ...context.repo,
+    commit_sha: context.sha,
+    per_page: 100,
+  });
+  const release = pulls.find(
+    (pull) =>
+      pull.merged_at &&
+      pull.merge_commit_sha === context.sha &&
+      pull.base.ref === 'main' &&
+      pull.base.repo?.full_name === repository &&
+      pull.head.ref === 'changeset-release/main' &&
+      pull.head.repo?.full_name === repository,
+  );
+  if (!release) return false;
+
+  const versions = await Promise.all(
+    [context.payload.before, context.sha].map(async (ref) => {
+      const { data } = await github.rest.repos.getContent({
+        ...context.repo,
+        ref,
+        path: 'package.json',
+      });
+      if (data.encoding !== 'base64' || typeof data.content !== 'string') {
+        throw new Error(`Could not read package.json at ${ref}.`);
+      }
+      return JSON.parse(Buffer.from(data.content, 'base64').toString('utf8')).version;
+    }),
+  );
+  return isVersionIncrease(...versions);
+}