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/src/versioning.rs

@@ -50,7 +50,7 @@ impl EntityVersioningService {
                 changed_at,
                 changed_by,
                 COALESCE(fields_changed, '{}') as fields_changed
-            FROM knowledge_node_version
+            FROM memory_entity_version
             WHERE entity_id = $1
             ORDER BY version_num DESC
             "#,
@@ -75,7 +75,7 @@ impl EntityVersioningService {
                 changed_at,
                 changed_by,
                 COALESCE(fields_changed, '{}') as fields_changed
-            FROM knowledge_node_version
+            FROM memory_entity_version
             WHERE entity_id = $1 AND version_num = $2
             "#,
         )
@@ -112,7 +112,7 @@ impl EntityVersioningService {
                 changed_at,
                 changed_by,
                 COALESCE(fields_changed, '{}') as fields_changed
-            FROM knowledge_node_version
+            FROM memory_entity_version
             WHERE entity_id = $1 AND changed_at <= $2
             ORDER BY version_num DESC
             LIMIT 1
@@ -146,7 +146,7 @@ impl EdgeVersioningService {
                 changed_at,
                 changed_by,
                 COALESCE(fields_changed, '{}') as fields_changed
-            FROM knowledge_edge_version
+            FROM memory_edge_version
             WHERE edge_id = $1
             ORDER BY version_num DESC
             "#,
@@ -172,7 +172,7 @@ impl EdgeVersioningService {
                 changed_at,
                 changed_by,
                 COALESCE(fields_changed, '{}') as fields_changed
-            FROM knowledge_edge_version
+            FROM memory_edge_version
             WHERE edge_id = $1 AND version_num = $2
             "#,
         )
@@ -190,7 +190,7 @@ impl EdgeVersioningService {
                 changed_at,
                 changed_by,
                 COALESCE(fields_changed, '{}') as fields_changed
-            FROM knowledge_edge_version
+            FROM memory_edge_version
             WHERE edge_id = $1 AND version_num = $2
             "#,
         )