v0.40.0

Added

• plan-gate stage — Tech plan gate (Plannotator on spec-tech.md). Between Planning and Execution. Only in Tech Review/Code Diff modes.
• diff-gate stage — Code diff review gate (Plannotator review). Between Verification and Audit. Only in Code Diff mode.
• New review mode: Product Spec + Interface + Tech Review + Code Diff — adds diff-gate for maximum oversight.

Changed

• Review mode rename for clarity:
  • Only Product Spec → Product Spec Gate
  • Product Spec + Interface Choice → Product Spec + Interface Gates
  • All Above + Scopes In/Out → Product Spec + Interface + Scopes
  • All Above + Tech Review → Product Spec + Interface + Tech Review
• PHASE_NAMES expanded from 15 to 17. All integrations, plugins, tests, and docs updated.