chore(android): lock MainActivity to portrait

Operator feedback: landscape just stretches the phone-portrait
Compose layout awkwardly — every screen was sized for one column
of cards, so rotation produces wide rows of unrelated content with
big dead bands top and bottom. Until a dedicated tablet/landscape
layout exists, lock the activity to portrait via screenOrientation.

Revisit when a sw600dp resource set + multi-pane layouts land.

android/app/src/main/AndroidManifest.xml

@@ -22,9 +22,14 @@
         android:usesCleartextTraffic="true"
         tools:targetApi="34">
 
+        <!-- Portrait-locked until a tablet/landscape layout exists.
+             Current Compose screens are sized for phone-portrait;
+             landscape just stretches the column awkwardly. Revisit
+             this when a dedicated tablet layout lands. -->
         <activity
             android:name=".MainActivity"
             android:exported="true"
+            android:screenOrientation="portrait"
             android:theme="@style/Theme.Minstrel">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />