Add explicit LLM concurrency controls

docs/llm-concurrency-audit.md

@@ -20,6 +20,15 @@ Main gap versus the requested target architecture:
 - global concurrency is currently represented by existing `--llm-concurrency`,
 - scheduler implementation is semaphore-based and does not explicitly guarantee FIFO ordering.
 
+## Implementation Status (2026-05-12 Update)
+
+The targeted concurrency gaps identified in this audit have now been addressed:
+- explicit total/proposal/validation LLM concurrency controls are implemented in config/env/CLI,
+- legacy `llm-concurrency` settings are preserved as compatibility aliases to total concurrency,
+- proposal and validation schedulers are composed with a global total-cap scheduler,
+- scheduler default behavior is FIFO with context-aware queued cancellation and reliable permit release,
+- runner proposal worker fan-out is aligned with effective proposal concurrency.
+
 ## Audit Findings (Questions 1-14)
 
 1. **Does the current runner execute modules serially?**