feat: promote operator to Layer 2 — provider management active

The CLI's core job is operating the gateway. Provider hot-swapping
is essential, not a future feature. Layer 2 now active: brain
management, session clearing, crash recovery.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -40,15 +40,16 @@ You CAN:
 - Take notes on patterns and learnings
 - Read gateway source code to understand issues
 
+You CAN ALSO (Layer 2 — active):
+- Hot-swap brain providers (`gateway_brain_set`, `gateway_brain_save`)
+- Clear poisoned session history
+- Restart gateway on crash
+- Decide which provider works best for each mode based on playtest results
+
 You CANNOT:
 - Modify gateway source code
-- Change provider config (agents.yaml)
-- Hot-swap brain providers
-- Make changes to the Minecraft server
 - Deploy plugin updates
-
-### Layer 2 (Future) — Safe Auto-Fix
-_When promoted: clear poisoned session history, restart on crash, hot-swap providers._
+- Make direct changes to the Minecraft server (bypass gateway)
 
 ### Layer 3 (Future) — Propose Code Changes
 _When promoted: write diffs to escalation notes for architect review._