feat(workbench): requirement 003 with the gates and register contracts

Requirement 003 Operator Workbench (operator-confirmed 2026-11-11) and the contracts its work packages build on: gates.py keeps gate rules, branch parents and gate receipts in ~/.local/state/agents-council/gates.db (resolve takes the branch's own level, else the strictest of all parents; derive records the nearest ancestor tips; tree hashes everything a worktree holds through a temporary index). rasci.py gains --unpin, stamps every changed row with updated, and ranks a task after its after-dependencies.

🎯 Fix: 95 %
💥 Break: 3 %
💸 Cost: 100 %
⏱️ Time: 100 %
🛡️ Security: 100 %
🏆 Score: 92
🚦 Gate: ✅ 90/5, cost and time <= 100, security 100 %

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/requirements/README.md

@@ -6,3 +6,4 @@ skill defines the format.
 
 - [001 - Agent Orchestrator](001-agent-orchestrator.md)
 - [002 - Cosmos](002-cosmos.md)
+- [003 - Operator Workbench](003-operator-workbench.md)