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/setup-webos-sdk.mjs

@@ -0,0 +1,48 @@
+// Pinned host toolchains. SDL-webOS is prepared separately by webos-runtime.mjs.
+import fs from 'node:fs/promises';
+import path from 'node:path';
+import { spawnSync } from 'node:child_process';
+
+const root = path.resolve(import.meta.dirname, '..');
+const parent = path.join(root, '.build/toolchain');
+const sdk = path.join(parent, 'arm-webos-linux-gnueabi_sdk-buildroot');
+const assets = {
+  'darwin-arm64':
+    'https://github.com/webosbrew/native-toolchain/releases/download/webos-d7ed7ee.6/arm-webos-linux-gnueabi_sdk-buildroot_darwin-arm64.tar.bz2',
+  'darwin-x64':
+    'https://github.com/webosbrew/native-toolchain/releases/download/webos-d7ed7ee.6/arm-webos-linux-gnueabi_sdk-buildroot_darwin-x86_64.tar.bz2',
+  'linux-x64':
+    'https://github.com/openlgtv/buildroot-nc4/releases/download/webos-b17b4cc/arm-webos-linux-gnueabi_sdk-buildroot.tar.gz',
+  'linux-arm64':
+    'https://github.com/webosbrew/native-toolchain/releases/download/webos-d7ed7ee.6/arm-webos-linux-gnueabi_sdk-buildroot_linux-aarch64.tar.bz2',
+};
+const url = assets[`${process.platform}-${process.arch}`];
+if (!url) throw new Error(`No pinned webOS SDK for ${process.platform}/${process.arch}.`);
+if (/[\s]/.test(sdk)) throw new Error('Extract the webOS SDK in a path without spaces.');
+await fs.mkdir(parent, { recursive: true });
+try {
+  await fs.access(path.join(sdk, 'bin/arm-webos-linux-gnueabi-gcc'));
+} catch {
+  const archive = path.join(parent, path.basename(url));
+  const downloaded = spawnSync(
+    'curl',
+    ['--fail', '--location', '--retry', '3', '--silent', '--show-error', '--output', archive, url],
+    { stdio: 'inherit', timeout: 300000 },
+  );
+  if (downloaded.error) throw downloaded.error;
+  if (downloaded.status !== 0) throw new Error('webOS SDK download failed.');
+  const extracted = spawnSync(
+    'tar',
+    [url.endsWith('.bz2') ? '-xjf' : '-xzf', archive, '-C', parent],
+    { stdio: 'inherit', timeout: 120000 },
+  );
+  if (extracted.error) throw extracted.error;
+  if (extracted.status !== 0) throw new Error('webOS SDK extraction failed.');
+}
+const relocated = spawnSync('sh', [path.join(sdk, 'relocate-sdk.sh')], {
+  stdio: 'inherit',
+  timeout: 120000,
+});
+if (relocated.error) throw relocated.error;
+if (relocated.status !== 0) throw new Error('webOS SDK relocation failed.');
+console.log(`webOS SDK ready. Set WEBOS_NDK=${sdk}`);