fix: resolve 17 P2 defects and 5 P3 defects from pre-launch audit

Batch fix covering multiple modules:
- P2-01: HandRegistry Semaphore-based max_concurrent enforcement
- P2-03: Populate toolCount/metricCount from Hand trait methods
- P2-06: heartbeat_update_config minimum interval validation
- P2-07: ReflectionResult used_fallback marker for rule-based fallback
- P2-08/09: identity_propose_change parameter naming consistency
- P2-10: ClassroomMetadata is_placeholder flag for LLM failure
- P2-11: classroomStore userDidCloseDuringGeneration intent tracking
- P2-12: workflowStore pipeline_create sends actionType
- P2-13/14: PipelineInfo step_count + PipelineStepInfo for proper step mapping
- P2-15: Pipe transform support in context.resolve (8 transforms)
- P2-16: Mustache {{...}} → \${...} auto-normalization
- P2-17: SaaSLogin password placeholder 6→8
- P2-19: serialize_skill_md + update_skill preserve tools field
- P2-22: ToolOutputGuard sensitive patterns from warn→block
- P2-23: Mutex::unwrap() → unwrap_or_else in relay/service.rs
- P3-01/03/07/08/09: Various P3 fixes
- DEFECT_LIST.md: comprehensive status sync (43/51 fixed, 8 remaining)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

crates/zclaw-saas/src/relay/service.rs

@@ -629,7 +629,7 @@ pub async fn sort_candidates_by_quota(
     let now = std::time::Instant::now();
     // 先提取缓存值后立即释放锁，避免 MutexGuard 跨 await
     let cached_entries: HashMap<String, (i64, std::time::Instant)> = {
-        let guard = cache.lock().unwrap();
+        let guard = cache.lock().unwrap_or_else(|e| e.into_inner());
         guard.clone()
     };
     let all_fresh = provider_ids.iter().all(|pid| {
@@ -673,7 +673,7 @@ pub async fn sort_candidates_by_quota(
 
         // 更新缓存 + 清理过期条目
         {
-            let mut cache_guard = cache.lock().unwrap();
+            let mut cache_guard = cache.lock().unwrap_or_else(|e| e.into_inner());
             for (pid, remaining) in &map {
                 cache_guard.insert(pid.clone(), (*remaining, now));
             }