revert: restore memory_entity/memory_edge table names

knowledge_* namespace reserved for future agentic learning tables.
memory_* namespace used for facts, events, and entity graph.

- knowledge_node → memory_entity (reverted)
- knowledge_edge → memory_edge (reverted)
- Old provenance DAG (child_sha/parent_sha) renamed to
  memory_edge_provenance via migration 009
- Kept: runtime queries in versioning.rs, UUID casts, init_schema additions

crates/mem-store/migrations/005_workflows_schema.sql

@@ -18,8 +18,8 @@ CREATE TABLE IF NOT EXISTS temporal_workflow_links (
     run_id VARCHAR(255),                    -- Temporal run ID
     
     -- Memory Entity References (Optional - NULL until linked)
-    entity_id UUID REFERENCES knowledge_node(id) ON DELETE SET NULL,
-    edge_id UUID REFERENCES knowledge_edge(id) ON DELETE SET NULL,
+    entity_id UUID REFERENCES memory_entity(id) ON DELETE SET NULL,
+    edge_id UUID REFERENCES memory_edge(id) ON DELETE SET NULL,
     node_id BIGINT REFERENCES memory_node(id) ON DELETE SET NULL,
     
     -- Sync Status