fix: comprehensive security, stability, and code quality audit

Security:
- Force API key auth for LAN (non-loopback) requests; remove shipped dev key
- Block path-traversal in backup restore; require auth on backup endpoints
- SSRF protection: DNS resolve + private/loopback/link-local IP rejection
- AES-256-GCM encryption for HA tokens and MQTT passwords with auto-migration
- WebSocket auth migrated from query-string to first-message protocol
- Asset upload: extension allowlist, server-side mime, Content-Disposition
- Update installer: SHA256 verification, tar/zip member validation
- Tightened CORS (explicit methods/headers, no credentials)
- ADB serial regex allowlist, webhook rate-limit key fix, log scrubbing

Android:
- Root-capture: ordered teardown, screenrecord respawn watchdog, child reaping
- USB permission blocking API via CompletableDeferred
- Python init crash guard with fatal-error screen
- Moved root grant + QR generation off Main thread
- Cached PyObject engine for per-frame bridge calls
- Ordered ScreenCapture resource cleanup, allowBackup=false

Python:
- Replaced all asyncio.get_event_loop() with get_running_loop/to_thread
- Split color_strip_sources.py (1683->5 files) and color_strip_stream.py
  (1324->7 files) into packages
- Extracted FrameLimiter utility, migrated 9 stream loops
- Provider base-class reuse, WLED state caching + URL normalization
- Narrowed broad except-pass in WS routes, threading fixes in BaseStore

Frontend:
- XSS fix: escapeHtml on dynamic option labels, reconcile-based list renders
- Typed DOM helpers, safe localStorage access, AbortController listener hygiene
- openAuthedWs helper for first-message WS auth protocol
- Migrated remaining plain <select>s to IconSelect/EntitySelect

Design:
- WCAG AA primary color on light theme (#2e7d32, 5.4:1 contrast)
- Android TV 10-foot breakpoint (tv.css)
- Consolidated z-index tokens, unified easing, card-running GPU hints

server/tests/e2e/conftest.py

@@ -27,6 +27,8 @@ _test_assets_dir = str(_e2e_tmp / "test_assets")
 import ledgrab.config as _config_mod  # noqa: E402
 
 # Build a Config that mirrors production settings but with isolated paths.
+# Always inject a test API key so auth-enforcement tests have something
+# concrete to authenticate against (and reject when omitted).
 _original_config = _config_mod.Config.load()
 _test_config = _original_config.model_copy(
     update={
@@ -35,6 +37,7 @@ _test_config = _original_config.model_copy(
             assets_dir=_test_assets_dir,
             max_file_size_mb=_original_config.assets.max_file_size_mb,
         ),
+        "auth": _config_mod.AuthConfig(api_keys={"e2e": "e2e-test-api-key-12345"}),
     },
 )
 # Install as the global singleton so all subsequent get_config() calls