fix(server): guard persisted PR cache continuations

[alimek]

Summary

External PR reads could touch persisted storage or publish held values after current authority changed during an await. External summary/stack reads now use Effect Cache with the existing TTL and service epochs, isolated by authority and action scope. Trusted reads retain disk persistence and restart reuse.

 PR read
-  persisted get -> lookup -> serialize -> backing set
+  external: checked memory cache -> checked publication
+  trusted: existing persisted cache
 revision invalidation / held publication
+  current composite admission after waits, before effects

Revision invalidation preserves typed denial without disabling caching. Held diff, summary, detail and stats continuations recheck before publication/delivery. Existing write scopes and invoking refresh authority remain intact.

Stack base: access/04c3-pr-read-effects at exact accepted c14c83d5ce70dc6165d715ce255c42c8764c6b29; PR27 remains OPEN/unmerged. Only approved 04c3b2. Final PR write effects04c4 and05–14 remain deferred; ResourceGrantGuard stays CLOSED.

Refs #5, #1.

Evidence

• Before: removing the two held-record guards makes three permanent regressions fail: summary, stale diff and detail publish denied values after a Clock wait.
  After: 65 focused tests pass: 21 cache/storage cuts and controls, 44 service cache/refresh/scope controls. Final typed-fixture changes also pass their 14 affected tests.
• Real SQL + Deferred cuts cover grant/root/membership/action changes after external lookup, invalidation permits, revision read, UUID and backing-write continuation. External reads perform zero backing get/set/remove or digest; denial starts no alternate lookup and does not disable persistence. Trusted restart/expiry/revision, ordinary failure, coalescing and cancellation controls pass.
• Named ./node_modules/.bin/vp run --filter t3 typecheck, five-file lint/format and diff checks pass. Unselected tests use CLI name filters; no committed skips, full-repo checks or CI watching.

Merge Danger

Door: Two-way. Existing disk format and contracts unchanged.

Blast Radius: Bounded. PR read caches, refreshes and held values; external reads rebuild memory after restart. Source acceptance and integration remain coordinator work.

Model: gpt-6.1-sol. Harness: Codex.

[alimek]

Consolidated into #30 at the same accepted final source tree (b66e06e), now targeting feature/connection-resource-access. Closing this individual stack PR as superseded; its commits, review record and branch remain preserved. No feature activation or main/upstream merge. Tracking issues remain open until integration verification.