Add support settings UI and first-day check-in generator
Settings app: Support section with 4 fields — enabled toggle, proactive
detection toggle, anonymous feedback toggle, and portal URL text input.
Uses existing auto-save pattern (data-section/data-key attributes).
Defaults added to journal_default.json, allowed_sections in routes.py.
First-day check-in: segment-scheduled generator with pre-hook guard.
Zero-cost skip when onboarding isn't complete or <1 hour has elapsed.
One-shot — records firstday_checkin_sent in awareness state to prevent
repeat. Post-hook spawns a support agent chat with a warm check-in.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>