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

android/app/build.gradle.kts

@@ -45,7 +45,19 @@ android {
 
     buildTypes {
         release {
+            // TODO(minify): keep R8 disabled until Chaquopy reflection is
+            // verified end-to-end. Chaquopy resolves Kotlin classes & static
+            // methods (PythonBridge, UsbSerialBridge, Root) by name from
+            // Python via PyObject — silent stripping breaks the app at
+            // runtime, after release. proguard-rules.pro contains keep
+            // rules covering the known entry points, but until we have
+            // a release smoke test that exercises every PyObject path we
+            // do NOT ship a minified release.
             isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro",
+            )
             signingConfig = if (hasCiSigning) {
                 signingConfigs.getByName("release")
             } else {
@@ -97,6 +109,7 @@ chaquopy {
             // and falls back to numpy/Pillow alternatives on Android.
             install("Pillow")
             install("websockets")
+            install("cryptography")     // AES-GCM secret-box for HA/MQTT credentials
         }
     }
 }
@@ -114,6 +127,8 @@ dependencies {
     implementation("androidx.leanback:leanback:1.0.0")
     implementation("com.google.android.material:material:1.12.0")
     implementation("androidx.lifecycle:lifecycle-service:2.8.7")
+    implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.8.7")
+    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-android:1.8.1")
     // QR code generation for displaying server URL on TV
     implementation("com.google.zxing:core:3.5.3")
     // USB-serial drivers (CH340, CP2102, FTDI, Prolific, CDC-ACM) for