fix(pipeline): rebuild FTS5 index during incremental reindex

The incremental pipeline (pipeline_incremental.c) deletes the old DB and
dumps the merged graph via cbm_gbuf_dump_to_sqlite, which bypasses SQLite
triggers. The FTS5 table was left empty (0 rows) after every incremental
reindex, making search_graph return 0 results for all queries.

Fix: after persisting file hashes (the last step before returning), rebuild
the FTS5 index with DELETE + INSERT from nodes using cbm_camel_split for
camelCase token splitting.

Before: full reindex → 672 FTS rows, incremental → 0 FTS rows
After:  full reindex → 672 FTS rows, incremental → 672 FTS rows

Author: Your Name

src/pipeline/pipeline_incremental.c

@@ -405,15 +405,24 @@ int cbm_pipeline_run_incremental(cbm_pipeline_t *p, const char *db_path, cbm_fil
     cbm_log_info("incremental.dump", "rc", itoa_buf(dump_rc), "elapsed_ms",
                  itoa_buf((int)elapsed_ms(t)));
 
-    /* Persist file hashes for ALL files */
-    cbm_store_t *hash_store = cbm_store_open_path(db_path);
-    if (hash_store) {
-        persist_hashes(hash_store, project, files, file_count);
-        cbm_store_close(hash_store);
-    }
-
-    cbm_gbuf_free(existing);
-
-    cbm_log_info("incremental.done", "elapsed_ms", itoa_buf((int)elapsed_ms(t0)));
-    return 0;
-}
+    /* Persist file hashes for ALL files + rebuild FTS5 index */
+    cbm_store_t *hash_store = cbm_store_open_path(db_path);
+    if (hash_store) {
+        persist_hashes(hash_store, project, files, file_count);
+
+        /* Rebuild FTS5 index: the btree dump bypasses triggers, and incremental
+         * merge may add/remove nodes. Rebuild the entire index from scratch.
+         * cbm_camel_split is registered by cbm_store_open_path automatically. */
+        cbm_store_exec(hash_store, "DELETE FROM nodes_fts;");
+        cbm_store_exec(hash_store,
+            "INSERT INTO nodes_fts(rowid, name, qualified_name, label, file_path) "
+            "SELECT id, cbm_camel_split(name), qualified_name, label, file_path FROM nodes;");
+
+        cbm_store_close(hash_store);
+    }
+
+    cbm_gbuf_free(existing);
+
+    cbm_log_info("incremental.done", "elapsed_ms", itoa_buf((int)elapsed_ms(t0)));
+    return 0;
+}