When a phase completes, the offer_next step now checks whether CONTEXT.md
already exists for the next phase before presenting options.
- If CONTEXT.md is absent: /gsd-discuss-phase is the recommended first step
- If CONTEXT.md exists: /gsd-plan-phase is the recommended first step
Adds regression test asserting conditional routing is present.
Closes#2002
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
