Add Makefile targets to install and verify phase-memory with warden.

install-all uses uv tool install --with-editable for sibling phase-memory.
check-memory and verify-memory confirm warden can load experiential memory.

src/warden/memory.py

@@ -7,7 +7,8 @@ from typing import Any, Mapping, Optional
 
 _PHASE_MEMORY_ERROR = (
     "phase-memory is required for warden memory commands. "
-    "Install with: pip install phase-memory (or set PYTHONPATH to phase-memory/src)."
+    "From ~/ops-warden run: make install-memory (or make install-all). "
+    "Dev fallback: PYTHONPATH=../phase-memory/src"
 )
 
 # In-process cache: implicit activation is default; no separate `warden memory activate`