Extracts the two AlertDialog builders and the build() body-selection
logic into a new status_page_dialogs.dart part file, following the
same part-of-main.dart split pattern status_body.dart already used.
Pure extraction, no behavior change -- verified with dart analyze and
the full flutter test suite (94/94 passing).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011w2Pj4Ek3ZNMQVYcFHgXDY
