feat: news story cards in Android briefing screen

Replaces bare Story-N reaction rows with full NewsCard widgets: source label,
relative timestamp, linked headline, 2-line snippet, and 👍/👎 reactions.
Reads rss_items from message metadata (requires backend ≥ this sprint).

Adds url_launcher ^6.3.1 for opening article links in the browser.
Adds https/http <queries> entries to AndroidManifest for Android 11+.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pubspec.yaml

@@ -27,6 +27,7 @@ dependencies:
   flutter_markdown_plus: ^1.0.7
   google_fonts: ^8.0.2
   flutter_timezone: ^5.0.2
+  url_launcher: ^6.3.1
 
 dev_dependencies:
   flutter_test: