fix(server): auto-generate session index after import

After streaming or incremental import, automatically generate the
session index (chat_session table) so the frontend does not show
the "generate index" prompt when entering a conversation.

packages/server/src/import/stream-import.ts

@@ -16,6 +16,7 @@ import {
   analyzeIncrementalImport as sharedAnalyzeIncremental,
   incrementalImport as sharedIncrementalImport,
 } from '@openchatlab/node-runtime'
+import { generateSessionIndex, generateIncrementalSessionIndex } from '@openchatlab/core'
 import type {
   StreamImportResult,
   StreamImportDeps,
@@ -90,6 +91,13 @@ function buildStreamImportDeps(dbManager: DatabaseManager, onProgress?: ImportPr
       }
     },
     onProgress: onProgress ?? (() => {}),
+    postImportHook(db) {
+      try {
+        generateSessionIndex(db)
+      } catch {
+        /* non-fatal: frontend can regenerate via generate-index route */
+      }
+    },
     generateSessionId,
   }
 }
@@ -164,6 +172,13 @@ function buildIncrementalDeps(dbManager: DatabaseManager, onProgress?: ImportPro
       return openBetterSqliteDatabase(dbPath, { readonly: readonly ?? false, nativeBinding })
     },
     onProgress: onProgress ?? (() => {}),
+    postImportHook(db) {
+      try {
+        generateIncrementalSessionIndex(db)
+      } catch {
+        /* non-fatal */
+      }
+    },
   }
 }