v1.7.2: ship Android config import/export (#266)

- mhrv-rs:// deep links, QR scanner, clipboard banner, share sheet
- DEFLATE-compressed base64 encoding (~200 chars vs ~800 raw)
- Every import path requires explicit user confirmation; the dialog
  shows the new deployment IDs and a trust warning so an attacker
  posting a malicious mhrv-rs:// link in a public channel can't
  silently overwrite a user's auth_key + script_ids
- ZXing for QR generation/scanning (no Google Play Services)

Closes #266. Thanks @yyoyoian-pixel — the rebase from auto-import
to confirmation-gated import is exactly the right shape.

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 = 146
-        versionName = "1.7.1"
+        versionCode = 147
+        versionName = "1.7.2"
 
         // Ship all four mainstream Android ABIs:
         //   - arm64-v8a      — 95%+ of real-world Android phones since 2019