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-cli/src/query/faceted_search.rs

@@ -108,7 +108,7 @@ impl FacetedSearch {
         // Get entity types
         let entity_types = sqlx::query_as::<_, (String, i64)>(
             "SELECT entity_type, COUNT(*) as cnt 
-             FROM knowledge_node 
+             FROM memory_entity 
              WHERE deleted_at IS NULL 
              GROUP BY entity_type 
              ORDER BY cnt DESC 
@@ -128,7 +128,7 @@ impl FacetedSearch {
 
         // Get total count
         let total_count: (i64,) = sqlx::query_as(
-            "SELECT COUNT(*) FROM knowledge_node WHERE deleted_at IS NULL"
+            "SELECT COUNT(*) FROM memory_entity WHERE deleted_at IS NULL"
         )
             .fetch_one(&self.pool)
             .await
@@ -212,7 +212,7 @@ impl FacetedSearch {
         // Get relation types
         let relation_types = sqlx::query_as::<_, (String, i64)>(
             "SELECT relation_type, COUNT(*) as cnt 
-             FROM knowledge_edge 
+             FROM memory_edge 
              WHERE fact_invalid_at IS NULL AND deleted_at IS NULL 
              GROUP BY relation_type 
              ORDER BY cnt DESC 
@@ -232,7 +232,7 @@ impl FacetedSearch {
 
         // Get total count
         let total_count: (i64,) = sqlx::query_as(
-            "SELECT COUNT(*) FROM knowledge_edge WHERE fact_invalid_at IS NULL AND deleted_at IS NULL"
+            "SELECT COUNT(*) FROM memory_edge WHERE fact_invalid_at IS NULL AND deleted_at IS NULL"
         )
             .fetch_one(&self.pool)
             .await