fix: reconcile MCP delivery silence

[Codename-11]

Summary

• distinguish a quiet MCP connection with a live run from completed delivery that needs disposition
• resolve obsolete MCP recovery asks for terminal issues without rewriting Delivery milestones
• prevent MCP-quiet coordination requests from becoming duplicate Ready to Close blockers
• document MCP session identity, reconnection, and completion reconciliation behavior

Root cause

Forge correctly models MCP liveness per negotiated client connection, but the stale-session sweep treated every quiet connection as possible active work. Completed runs, terminal issues, and otherwise-ready issues could therefore retain an “MCP status unconfirmed” ask, and completion evaluation counted that recovery ask as an independent operator decision.

Impact

Desktop reconnects remain session-specific and do not falsely confirm older clients. Operators now see an active-run warning only when a run is actually active; completed delivery asks for an explicit disposition, terminal issues clear obsolete recovery noise, and safe completion evidence supersedes the redundant coordination warning.

Validation

• pnpm lint — passed with existing repository warnings
• pnpm typecheck — passed
• focused WorkSession, completion-candidate, and pin tests — 27/27 passed
• full suite — 1,513 passed; one unrelated persistent local database fixture collision was isolated, its exact orphaned row removed, and the previously failing pin test passed

Implements AXI-151