Publish Android releases to a self-hosted F-Droid repo

scripts/fdroid-publish.sh builds a signed arm64 APK and adds it to an
F-Droid repo in a given directory, creating the app signing key and the
repo on first use. The versionCode is the commit count, so any commit can
ship without a manual version bump.

Release builds are signed when src-tauri/gen/android/keystore.properties
exists and stay unsigned otherwise. The manifest picks up the deep-link
plugin's intent filter, which every build regenerates and was never
committed.

src-tauri/gen/android/app/src/main/AndroidManifest.xml

@@ -28,6 +28,21 @@
                 <!-- AndroidTV support -->
                 <category android:name="android.intent.category.LEANBACK_LAUNCHER" />
             </intent-filter>
+            <!-- DEEP LINK PLUGIN. AUTO-GENERATED. DO NOT REMOVE. -->
+            <intent-filter >
+                <action android:name="android.intent.action.VIEW" />
+                <!-- ChromeOS ARC++ uses a different action for deep links -->
+                <action android:name="org.chromium.arc.intent.action.VIEW" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <category android:name="android.intent.category.BROWSABLE" />
+                <data android:scheme="mtgc" />
+                <data android:host="auth" />
+                <data android:path="/callback" />
+                
+                
+                
+            </intent-filter>
+            <!-- DEEP LINK PLUGIN. AUTO-GENERATED. DO NOT REMOVE. -->
         </activity>
 
         <provider