feat: desktop-style UI + docker build scripts, fix ping crash

- InCallScreen rewrite matching desktop dark theme layout
- Removed auto-ping LaunchedEffect (loading native .so early via
  pingRelay crashes jemalloc on Android 16 MTE)
- Added Docker build scripts (Dockerfile.android-builder + build-android-docker.sh)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

skills-lock.json

@@ -0,0 +1,10 @@
+{
+  "version": 1,
+  "skills": {
+    "caveman": {
+      "source": "JuliusBrussee/caveman",
+      "sourceType": "github",
+      "computedHash": "aa7939fc4d1fe31484090290da77f2d21e026aa4b34b329d00e6630feb985d75"
+    }
+  }
+}