chore: bump versions to 1.7.7 (Cargo + Android)

The v1.7.7 tag commit (6885800) only updated the changelog; the
version field edits failed earlier due to file-state-changed-mid-edit
race. Fixing forward — Cargo.toml + build.gradle.kts now show 1.7.7
properly.

Workflow will build from main HEAD on workflow_dispatch, so the
v1.7.7 release-page artifacts will have the correct internal version
even though the tag commit itself doesn't include the version bump.

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 = 151
-        versionName = "1.7.6"
+        versionCode = 152
+        versionName = "1.7.7"
 
         // Ship all four mainstream Android ABIs:
         //   - arm64-v8a      — 95%+ of real-world Android phones since 2019