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/screenshots.mjs

@@ -0,0 +1,63 @@
+// Capture documentation from the actual native desktop renderer, not a browser.
+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 docs = path.join(root, 'docs');
+const scratch = path.join(root, '.build');
+await fs.mkdir(docs, { recursive: true });
+await fs.mkdir(scratch, { recursive: true });
+
+function run(command, args) {
+  const result = spawnSync(command, args, { cwd: root, stdio: 'inherit', timeout: 120000 });
+  if (result.error) throw result.error;
+  if (result.status !== 0) throw new Error(`${command} exited with status ${result.status}`);
+}
+
+// Force the desktop feature set even after a previous all-features lint/build.
+run('cargo', ['build', '--locked', '--package', 'luma', '--no-default-features']);
+const binary = path.resolve(root, process.env.CARGO_TARGET_DIR ?? 'target', 'debug/luma');
+const temporary = await fs.mkdtemp(path.join(scratch, 'documentation-'));
+const preferences = path.join(temporary, 'preferences.json');
+const configuration = {
+  language: 'en',
+  background: 'dunes',
+  hour_24: false,
+  show_home_names: false,
+  show_weather: true,
+  weather_location: null,
+  hidden: [],
+  input_modes: {},
+  reduced_motion: false,
+};
+try {
+  for (const [name, script] of [
+    ['home', 'home,down'],
+    ['apps', 'apps,down'],
+    ['settings', 'settings,down'],
+    ['inputs', 'settings,down,down,down,down,enter'],
+  ]) {
+    // Independent state makes screenshots stable regardless of capture order.
+    await fs.writeFile(preferences, JSON.stringify(configuration));
+    run(binary, [
+      '--assets',
+      path.join(scratch, 'assets'),
+      '--preferences',
+      preferences,
+      '--time',
+      '2026-10-22T20:41:00+02:00',
+      '--script',
+      script,
+      '--frames',
+      '90',
+      '--capture-scale',
+      '1',
+      '--screenshot',
+      path.join(docs, `${name}.png`),
+    ]);
+    console.log(`Native screenshot: docs/${name}.png (1920×1080)`);
+  }
+} finally {
+  await fs.rm(temporary, { recursive: true, force: true });
+}