TASK-051-001: Audit RFC9111 Consumers

Used Roslyn Navigator to find all references to RFC9111 key types
(CacheStore, CacheEntry, CachePolicy, CacheFreshnessEvaluator, CacheControl).
Identified 25 consumer files: 5 production (CacheBidiStage + config/factory),
20 test files (caching tests, stream tests, integration tests, hosting tests).
Confirmed RFC9111 is self-contained with no unexpected dependencies.

Acceptance criteria:
- Run Roslyn Navigator find_references on all key types ✓
- Produce complete consumer file list ✓
- Confirm consumers are CacheBidiStage and test files only ✓

Author: st0o0

.maggus/features/feature_051.md

@@ -60,10 +60,10 @@ imports this namespace so that no `using` directive is missed.
 **Model:** haiku
 
 **Acceptance Criteria:**
-- [ ] Run Roslyn Navigator `find_references` on `CacheStore`, `CacheEntry`, `CachePolicy`,
+- [x] Run Roslyn Navigator `find_references` on `CacheStore`, `CacheEntry`, `CachePolicy`,
       `CacheFreshnessEvaluator`, `CacheControl`
-- [ ] Produce complete consumer file list
-- [ ] Confirm consumers are the `CacheBidiStage` and test files only
+- [x] Produce complete consumer file list
+- [x] Confirm consumers are the `CacheBidiStage` and test files only
 
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