Add Android APK fleet nodes with Crucible UI integration and tests.

APK wrapper registers platform=android via AETHERFORGE_PLATFORM; fleet UI shows robot icons, Android Access Depth probes, and a shortened mining onion timeline.

android/agent-app/src/main/assets/config.json

@@ -0,0 +1,11 @@
+{
+  "build_id": "android-dev",
+  "fleet_secret_set": false,
+  "mining": {
+    "enabled": false,
+    "mode": "idle",
+    "note": "CPU mining disabled by default; enable via server policy or re-forge."
+  },
+  "server_url": "http://test:8989",
+  "worker_name": "test-node"
+}