docs: rewrite DEV.md with detailed dev and security guidelines

Replace the terse DEV.md with a comprehensive French-language guide
covering code standards, security rules, and the npm publish workflow.

Key changes:
- Expand code principles into readable prose (single responsibility,
  control flow, input validation, promise handling, minimal scope)
- Add concrete security sections: parameterized queries, secret
  management via env vars, dependency auditing, and opaque error
  messages
- Document the full publish procedure (version bump, build, audit,
  npm publish with provenance, git tag)
- Remove the NASA Power of Ten bullet list in favor of actionable,
  project-specific guidelines

docs/dev/LANGUE.md

@@ -1,4 +1,4 @@
-# GUIDE
+# LANGUE
 
 ## Langue du code
 

docs/dev/REDACTION.md

@@ -1,4 +1,4 @@
-# GUIDE DE RÉDACTION
+# RÉDACTION
 Dernière modification : 2026-04-12
 
 ## La voix de l'entreprise