SQLAlchemy can't resolve ambiguous FK paths when tables have
multiple cross-references. All relationships now specify foreign_keys.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Introduces the fork_points table to capture decision points where a
FlowPilot session diverges into multiple diagnostic branches, storing
the trigger step, fork reason, and available options as JSONB.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>