chore: mosaic upgrade — centralize AGENTS.md, update CLAUDE.md pointer

CLAUDE.md replaced with thin pointer to ~/.config/mosaic/AGENTS.md.
SOUL.md and AGENTS.md now managed globally by the Mosaic framework.

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

CLAUDE.md

@@ -1,14 +1,10 @@
-# Compatibility Pointer
+# CLAUDE Compatibility Pointer
 
-This repository uses an agent-neutral Mosaic standards model.
+This file exists so Claude Code sessions load Mosaic standards.
 
-Authoritative repo guidance is in `AGENTS.md`.
+## MANDATORY — Read Before Any Response
 
-Load order for Claude sessions:
+BEFORE responding to any user message, READ `~/.config/mosaic/AGENTS.md`.
 
-1. `SOUL.md`
-2. `~/.config/mosaic/STANDARDS.md`
-3. `AGENTS.md`
-4. `.mosaic/repo-hooks.sh`
-
-If you were started from `CLAUDE.md`, continue by reading `AGENTS.md` now.
+That file is the universal agent configuration. Do NOT respond until you have loaded it.
+Then read the project-local `AGENTS.md` in this repository for project-specific guidance.