Fix persistent quorum consumer receipt convergence

[VerifiedOrganic]

Outcome

This change completes the bounded persistent consumer and protected fenced-transition path required by the ePDG three-voter session store. It preserves one immutable request identity through ambiguity, removes redundant quorum reads from ordinary mutations, and keeps authenticated request lanes warm without charging connection maintenance to an admitted operation deadline.

Safety properties retained

• A possibly transmitted mutation is never replayed at another voter.
• NotTransmitted remains the only safe same-request failover boundary.
• Ambiguous fenced transitions converge through exact read-only receipt/status lookup.
• Lease/fence, tenant/scope, request ID, transition token, and expected-record checks remain exact.
• Logical and physical operation bounds are unchanged; this does not raise timeouts.
• Warm-lane refill and reauthentication are serialized, bounded, cancellation-safe, and yield to admitted calls.

Evidence

• Focused persistent-consumer, ambiguity, cancellation, warm-refill, prepared-transition, and write-budget tests are retained.
• The complete hosted workflow set passed at production/test head 59c89725; later CI-only commits isolate timing-sensitive contracts into fresh processes without altering product behavior. The current head must pass the complete hosted matrix before merge.
• Independent reviews approved the production receipt/warm-lane series, deterministic timing tests, and both narrow CI-isolation diffs.
• The downstream ePDG candidate will pin the final merged SDK commit, not this branch head.
• OpenShift 4.18 CRC build, deploy, call-path timing, and restart/delete qualification remain downstream acceptance gates after that immutable pin; prior deployments are not claimed as evidence for the final merged revision.

Related issues

Implements the remaining transport and fenced-mutation foundations tracked in #695, #696, #702, and #707. Issue closure remains tied to each issue's own acceptance evidence.

Dependency order

Merge this SDK PR first. Then pin the ePDG PR to the SDK merge commit, build that exact tree, and run the OpenShift 4.18 lifecycle and call-path gates before merging the product PR.

[VerifiedOrganic]

Hosted failures on the prior head were reciprocal test-resource contention: the snapshot/compaction fleet and a separate 100 ms activation proof selected different victims in different jobs. Commit 84f0b83 serializes only the shared three-voter integration fixture; it does not change production deadlines, quorum, durability, mutation, or receipt behavior. Independent review approved exact diff SHA-256 812b5c5934e40cd0d595f8689bc686a4937dd2e9a2c2e4b721b53dde2ea87465. Local focused compaction, full native 28-test, full i686 28-test, fmt, diff-check, and all-target/all-feature clippy gates pass. A fresh hosted matrix is now running.