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/007_versioning_schema.sql

@@ -5,7 +5,7 @@
 BEGIN;
 
 -- Entity version snapshots (immutable)
-CREATE TABLE IF NOT EXISTS knowledge_node_version (
+CREATE TABLE IF NOT EXISTS memory_entity_version (
     id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
     entity_id VARCHAR(255) NOT NULL,
     version_num INTEGER NOT NULL,
@@ -28,7 +28,7 @@ CREATE TABLE IF NOT EXISTS knowledge_node_version (
 );
 
 -- Edge version snapshots
-CREATE TABLE IF NOT EXISTS knowledge_edge_version (
+CREATE TABLE IF NOT EXISTS memory_edge_version (
     id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
     edge_id UUID NOT NULL,
     version_num INTEGER NOT NULL,
@@ -52,22 +52,22 @@ CREATE TABLE IF NOT EXISTS knowledge_edge_version (
 
 -- Indexes for efficient lookups
 CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_entity_version_entity_id 
-    ON knowledge_node_version(entity_id, version_num DESC);
+    ON memory_entity_version(entity_id, version_num DESC);
 
 CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_entity_version_changed_at 
-    ON knowledge_node_version(changed_at DESC);
+    ON memory_entity_version(changed_at DESC);
 
 CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_entity_version_changed_by 
-    ON knowledge_node_version(changed_by);
+    ON memory_entity_version(changed_by);
 
 CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_edge_version_edge_id 
-    ON knowledge_edge_version(edge_id, version_num DESC);
+    ON memory_edge_version(edge_id, version_num DESC);
 
 CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_edge_version_changed_at 
-    ON knowledge_edge_version(changed_at DESC);
+    ON memory_edge_version(changed_at DESC);
 
 CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_edge_version_changed_by 
-    ON knowledge_edge_version(changed_by);
+    ON memory_edge_version(changed_by);
 
 -- Immutability enforcement: version tables are append-only
 CREATE OR REPLACE FUNCTION prevent_version_table_modification()
@@ -77,19 +77,19 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
-CREATE TRIGGER knowledge_node_version_immutable
-    BEFORE UPDATE OR DELETE ON knowledge_node_version
+CREATE TRIGGER memory_entity_version_immutable
+    BEFORE UPDATE OR DELETE ON memory_entity_version
     FOR EACH ROW EXECUTE FUNCTION prevent_version_table_modification();
 
-CREATE TRIGGER knowledge_edge_version_immutable
-    BEFORE UPDATE OR DELETE ON knowledge_edge_version
+CREATE TRIGGER memory_edge_version_immutable
+    BEFORE UPDATE OR DELETE ON memory_edge_version
     FOR EACH ROW EXECUTE FUNCTION prevent_version_table_modification();
 
 COMMIT;
 
 -- Rollback (for reference):
--- DROP TRIGGER knowledge_node_version_immutable ON knowledge_node_version;
--- DROP TRIGGER knowledge_edge_version_immutable ON knowledge_edge_version;
+-- DROP TRIGGER memory_entity_version_immutable ON memory_entity_version;
+-- DROP TRIGGER memory_edge_version_immutable ON memory_edge_version;
 -- DROP FUNCTION prevent_version_table_modification();
--- DROP TABLE knowledge_node_version;
--- DROP TABLE knowledge_edge_version;
+-- DROP TABLE memory_entity_version;
+-- DROP TABLE memory_edge_version;