Add server-side duplicate detection in gitea_create_issue that re-queries
open and recently closed issues at mutation time, blocks normalized title
matches unless the operator explicitly approves a split, and validates LLM
duplicate-search summaries via review_proofs.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Add gitea_route_task_session and role_session_router to fail closed when
reviewer tasks start under author-bound MCP sessions. Block author-side
issue creation fallback after wrong_role_stop. Add handoff proof helper and
tests.
Closes#206
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>