Fix Fossify Messages GUI fixture normalization

[panDing19]

Problem

TGUI46's Fossify Messages fixture mixes flat SMS rows with threaded message rows. The initializer only handled one shape at a time, so mixed fixtures could fail normalization or lose message content before SQLite injection.

Affected tasks

• TGUI46_job_failure_triage_workmail_sms_notes

Fix

• Normalize message ids, timestamps, text fields, and outgoing status across the observed field aliases.
• Normalize threaded rows independently.
• Group flat rows by thread_id while preserving mixed flat/threaded fixture order.
• Add a regression test using the real TGUI46 Fossify Messages fixture.

Tests

• uv run pytest tests/test_mobile_gui_init.py -q