chore(docs): add JSDoc guardrail to always-on guardrails in CLAUDE.md

Author: PierreBrisorgueil

CLAUDE.md

@@ -53,6 +53,7 @@ The `.claude/` folder contains embedded settings, skills, and agents that are av
 - Avoid risky renames or moves of core stack paths used by downstream merges
 - Keep changes minimal and merge-friendly for downstream projects
 - Flag security or mergeability risks explicitly in reviews
+- Every new or modified function must have a JSDoc header: one-line description, `@param` for each argument, `@returns` for any non-void return value (always include `@returns` for async functions to document the resolved value)
 
 ## Available embedded skills