fix: resolve remaining CI failures — mapper FK mismatch and lint errors
Backend: Use string-form foreign_keys on SessionBranch.session to match
AISession.branches — mixed column-object vs string-expression caused
SQLAlchemy mapper initialization conflict.
Frontend lint fixes:
- Remove unused _escalateUploads, _intakeUploads destructured vars
- Remove unused _ticket, _chatId, _pinned parameters
- Replace empty interface with type alias (public-templates.ts)
- Suppress setState-in-effect in SimilarSessions, SidebarStatsBar,
FlowPilotAnalyticsPage (intentional prop sync patterns)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
69edf5378b