refactor: break up NerveCenter god class into cohesive modules (audit #3)

nerve-center.ts (1,969 lines) is now a 763-line facade with an unchanged
public API over: coordination-types, coordination-client (retry + circuit
breaker), job-board (incl. release_job), lock-registry, lock-paths,
enforced-perms, state-store, protocol-transcript, core-services.
contextManager is typed (CoordinationContext) instead of any.

Includes the dependent work that landed on top during the same session:
atomic cross-process state persistence wired into StateStore (audit #5),
canonical cross-surface tool manifest, lock path canonicalization test,
ARCHITECTURE.md and docs/RELEASING.md (audits #26/#27 docs).

tsc --noEmit clean; bun test 160/160.