Add priority hint to device profiles list

- Shows hint when 2+ profiles exist explaining order determines priority
- Appears as flat list item at bottom, less intrusive than card
- Prevents dragging hint item, keeps it at bottom
- Uses book icon for informational guidance

app/src/main/res/values/strings.xml

@@ -242,6 +242,7 @@
     <string name="profiles_maindevice_encryptionkey_explanation">AirPods send a status message, part of which is encrypted. The encryption key allows CAPod to decrypt the full message. You need one-time access to a MacBook.</string>
     <string name="profiles_key_invalid_format">Invalid key format</string>
     <string name="profiles_key_expected_format">Expected format: %1$s</string>
+    <string name="profiles_priority_hint">Profile order determines priority. Drag profiles to reorder them - profiles higher in the list take precedence when multiple devices match.</string>
 
     <!-- Unsaved changes dialog -->
     <string name="general_unsaved_changes_title">Unsaved Changes</string>