v0.5.1 — UI: map ring, ⌖ crosshair, source-color dots, bottom START

- Larger main-screen map circle (220 -> 300dp) wrapped in a threat-color ring
  (green/yellow/orange/red while scanning, gray idle).
- User position renders as a ⌖ crosshair; map geodata color-coded by source
  (Flock/DeFlock red, Waze blue, Citizen purple) in both the main circle and
  the floating overlay bubble.
- START button moved to the bottom of the screen.
- README brought current: COMMERCIAL source + overlay documented, Waze-via-proxy
  and the CI release pipeline described, architecture/permissions/changelog
  updated, build reqs corrected to JDK 17 / SDK 35.

versionCode 16 -> 17, versionName 0.5.0 -> 0.5.1.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015jgJnzMr2bdNuWcDX2xRUR

app/build.gradle.kts

@@ -12,8 +12,8 @@ android {
         applicationId = "org.soulstone.overwatch"
         minSdk = 26
         targetSdk = 35
-        versionCode = 16
-        versionName = "0.5.0"
+        versionCode = 17
+        versionName = "0.5.1"
     }
 
     buildTypes {