Add CLAUDE.md self-update checkpoint

Adds an explicit rule at the top of CLAUDE.md requiring a check after
every codebase change: routes, models, migrations, files, limits,
security patterns, Docker infra, and stack versions each map to the
specific section that must be updated.

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

CLAUDE.md

@@ -2,6 +2,21 @@
 
 This file provides permanent, authoritative guidance to Claude Code for every session. All sections below reflect the actual codebase state and must be kept up-to-date as the project evolves.
 
+## CLAUDE.md self-update checkpoint
+
+**After every change to the codebase**, before committing, check whether CLAUDE.md needs updating:
+
+- New route added → update **All API Endpoints** and **Frontend Routes** tables
+- New DB model or column → update **Database Models**
+- New migration → update **Migration chains**
+- New file or directory → update **File & Folder Tree**
+- New limit or default value changed → update **Default Values & Limits**
+- New dependency, auth mechanism, or security pattern → update **Security Standards**
+- New Docker service, volume, network, or env var → update **Docker Infrastructure**
+- Stack version changed → update **Stack**
+
+This check is mandatory — treat it the same as updating STATUS.md.
+
 ---
 
 ## Stack