Adds an optional advisor mode to discuss-phase that provides research-backed
comparison tables before asking users to make decisions. Activates when
USER-PROFILE.md exists, degrades gracefully otherwise.
New agent: gsd-advisor-researcher -- spawned in parallel per gray area,
returns structured 5-column comparison tables calibrated to the user vendor
philosophy preference (full_maturity/standard/minimal_decisive).
Workflow changes (discuss-phase.md):
- Advisor mode detection in analyze_phase step
- New advisor_research step spawns parallel research agents
- Table-first discussion flow in discuss_areas when advisor mode active
- Standard conversational flow unchanged when advisor mode inactive
