📝 docs: make AGENTS.md canonical, CLAUDE.md a shim

AGENTS.md is read by every agent tool; CLAUDE.md now imports it so the
guidance lives in one file instead of two that drift.

Claude-Session: https://claude.ai/code/session_0165h5hvmWJfxaEN4y9t5m1U

Author: luiscosio

CLAUDE.md AGENTS.mdCLAUDE.md renamed to AGENTS.md

@@ -1,4 +1,4 @@
-# CLAUDE.md
+# AGENTS.md
 
 This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
 

README.md

@@ -62,7 +62,7 @@ python -m http.server 8000
 ```
 control-overlays-selector/
 ├── index.html                    # Main web application (vanilla JS)
-├── CLAUDE.md                     # AI assistant guidance
+├── AGENTS.md                     # AI assistant guidance
 ├── README.md                     # This file
 │
 ├── nist_catalog/                 # NIST SP 800-53 source data