feat(graph): tag/entity 虚拟节点落库为真实节点（合成 path 命名空间）

ai_xiaopei

2026-08-21 efd6a8d9902e79df852012bf4a3fa94e1f8889cb

 internal/index/fts.go

@@ -21,9 +21,7 @@
         title,
         content,
         tags,
         entities,
         content='nodes',
         content_rowid='id'
         entities
      )
   `)
   return err