Release 2.7.3.1: harden proxy recovery, updates and local API.

Restore orphaned system proxy after crash, require update SHA-256, add macOS /api auth token, fix UDP ping false positives, HTTPS-only subscriptions, and keep the UI responsive during connect.

Co-authored-by: Cursor <cursoragent@cursor.com>

android/app/build.gradle.kts

@@ -14,7 +14,7 @@ android {
         targetSdk = 35
         // versionCode = major*1_000_000 + minor*10_000 + patch*100 + build
         versionCode = 2_070_201
-        versionName = "2.7.2+1"
+        versionName = "2.7.3+1"
         vectorDrawables.useSupportLibrary = true
         ndk {
             abiFilters += listOf("arm64-v8a", "armeabi-v7a", "x86_64")