refactor: output channel interface (payload/meta/type) + memory fixes

- Redesign output_send__ tools: content JSON string -> structured
  payload/meta/type params for LLM reliability
- executeOutputSendTool: route by type with capability check
- executeOutputSendHelp: show meta format + type enum
- Updated system prompt rules for new interface
- docToTriples: use jieba exact mode adjacent co-occurrence
- Unify vector space: Doc.Vector field, ContextToDoc vectorizer,
  ReindexWithVectorizer on startup

internal/agent/core/context.go

@@ -200,7 +200,7 @@ func (c *RelevanceContext) Prune(currentInput string, topK int, docStore *docume
 				Response:  s.event.Response,
 			}
 		}
-		doc, err := docStore.ContextToDoc("context_archived", entries)
+		doc, err := docStore.ContextToDoc("context_archived", entries, c.embedder)
 		if err == nil && doc != nil {
 			archived = len(archive)
 		}