refactor(memory): add PilotWritePipeline and enrich extraction schema

- Add dedicated PilotWritePipeline (statement → triplet → graph_build → layer-1 dedup, no Neo4j write)
- Add type_description/predicate_description fields across entity and triplet models, Cypher queries, and graph builders
- Refactor data_pruning with LRU cache and snapshot support; skip assistant chunks in extraction
- Remove strict Predicate enum whitelist; support statement_text alias in legacy extractor
- Wire PipelineSnapshot through preprocessing and emotion extraction for debug tracing
- Add PILOT_RUN_USE_REFACTORED_PIPELINE env toggle for pipeline selection

api/app/repositories/neo4j/cypher_queries.py

@@ -92,6 +92,7 @@ SET e.name = CASE WHEN entity.name IS NOT NULL AND entity.name <> '' THEN entity
         THEN entity.expired_at ELSE e.expired_at END,
     e.entity_idx = CASE WHEN e.entity_idx IS NULL OR e.entity_idx = 0 THEN entity.entity_idx ELSE e.entity_idx END,
     e.entity_type = CASE WHEN entity.entity_type IS NOT NULL AND entity.entity_type <> '' THEN entity.entity_type ELSE e.entity_type END,
+    e.type_description = CASE WHEN entity.type_description IS NOT NULL AND entity.type_description <> '' THEN entity.type_description ELSE coalesce(e.type_description, '') END,
     e.description = CASE
         WHEN entity.description IS NOT NULL AND entity.description <> ''
          AND (e.description IS NULL OR size(e.description) = 0 OR size(entity.description) > size(e.description))
@@ -147,6 +148,7 @@ MATCH (object:ExtractedEntity {id: rel.target_id, end_user_id: rel.end_user_id})
 // Avoid duplicate edges across runs for the same endpoints
 MERGE (subject)-[r:EXTRACTED_RELATIONSHIP]->(object)
 SET r.predicate = rel.predicate,
+    r.predicate_description = rel.predicate_description,
     r.statement_id = rel.statement_id,
     r.value = rel.value,
     r.statement = rel.statement,

api/app/repositories/neo4j/graph_saver.py

@@ -44,6 +44,7 @@ async def save_entities_and_relationships(
             'source_id': edge.source,
             'target_id': edge.target,
             'predicate': edge.relation_type,
+            'predicate_description': edge.relation_type_description,
             'statement_id': edge.source_statement_id,
             'value': edge.relation_value,
             'statement': edge.statement,
@@ -297,6 +298,7 @@ async def save_dialog_and_statements_to_neo4j(
                     'source_id': edge.source,
                     'target_id': edge.target,
                     'predicate': edge.relation_type,
+                    'predicate_description': edge.relation_type_description,
                     'statement_id': edge.source_statement_id,
                     'value': edge.relation_value,
                     'statement': edge.statement,