chore: bump versions to 1.7.8 (Cargo + Android)

Patch release for the auto-blacklist of timeout-saturated deployments
shipped via #319. No new features; bugfix only — cargo, gradle, and
changelog bumps in lockstep so the release workflow can ship matching
artifacts.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

android/app/build.gradle.kts

@@ -14,8 +14,8 @@ android {
         applicationId = "com.therealaleph.mhrv"
         minSdk = 24 // Android 7.0 — covers 99%+ of live devices.
         targetSdk = 34
-        versionCode = 152
-        versionName = "1.7.7"
+        versionCode = 153
+        versionName = "1.7.8"
 
         // Ship all four mainstream Android ABIs:
         //   - arm64-v8a      — 95%+ of real-world Android phones since 2019