feat(memory): add lifecycle operations

docs/memory-graph-runtime.md

@@ -26,6 +26,13 @@ with `markitect-tool`.
   policy check plus per-node policy checks, returns source-grounded context
   items, preserves safe denied diagnostics, and emits an audit event in the
   result envelope.
+- `MemoryRuntimeService.apply_retention()` marks stale memories for review or
+  transitions old memories to `delete_requested` without physical deletion.
+- `MemoryRuntimeService.refresh_memory()` clears stale markers and records a
+  refresh event.
+- `MemoryRuntimeService.compact_memory()` creates a deterministic summary node,
+  preserves source spans/provenance, optionally retires source nodes, and appends
+  a compaction event.
 
 ## Boundary