feat(server): capture admission program generation per request

[SunSi12138]

Scope

Implements #322 as the stacked follow-up to #319, now restacked directly onto dev after the lower stack landed.

This PR remains limited to immutable Dynamic Admission program publication/capture and per-request generation lifetime. It does not add a runtime mutation API, migrate limiter state, or redesign ResourceGovernor/decode/pre-admission-stream ownership.

Implementation

• compose enabled Dynamic Admission as one immutable AdmissionProgram generation; disabled remains a no-controller publication;
• capture the current admission publication once at the accepted Request boundary in RequestLoop;
• explicitly pass the captured program into one-way/two-way dispatch and queued continuations;
• remove downstream request-path reads of the server's current admission controller/publication;
• bind enabled-generation lifetime to one linear refcount ownership chain, transferring the captured generation use to ServerCallCancellationState when admission state is created and releasing it exactly once from terminal cleanup;
• keep the disabled request path allocation/refcount free;
• preserve existing admission leases, retained compressed payloads, decode permits, pre-admission stream permits, call permits, cancellation/activation arbitration, and terminal cleanup paths;
• retain deterministic publication hooks/diagnostics for the [Server][DynamicAdmission] Capture immutable AdmissionProgram generation per request #322 race matrix;
• adapt the existing request-scope reflection harness to the generation-aware dispatch signatures after restack.

Validation

Final exact head: ada8dde71b58a480b7b843cea638f1e0d43cc1aa

PR Quick: 32993893194, attempt 2 — passed on the exact branch head.

• Formatting: passed
• Debug build: passed, 0 warnings / 0 errors
• Release build: passed, 0 warnings / 0 errors
• Generated assembly Runtime-reference verification: passed
• Unit Tests: passed (1227 total)
• Generator Tests: passed
• Load Test Tests: passed
• Integration Tests: passed
• NativeAOT transport/topology smoke: passed
• Pack / SDK / metadata / dependency / package smoke gates: passed
• Oneway demo: passed
• Load Smoke: passed
• Chaos Smoke (120s sharedmemory): passed
• Codec compatibility producer/verify/browser evidence matrix: passed, including Windows ARM64 on attempt 2

CodeQL: 32993806558 — passed on the same exact head.

The first PR Quick attempt exposed and led to fixes for two restack-only test harness compatibility issues. A subsequent isolated shared-memory control-channel test failure did not reproduce on failed-job rerun; the complete attempt-2 quick job and all rerun codec jobs passed.

Residual risk

No known correctness or CI blocker remains for this slice. Runtime Admission mutation/state migration remains intentionally out of scope for later #264 slices.

Refs #322, #319, #273, #264.