Fix 6 bugs found during code review

- Fix NameError: pass state to _render_vace_settings (tab_batch_ng.py)
- Fix non-atomic sync_to_db: use BEGIN IMMEDIATE transaction with rollback
- Fix create_secondary() missing db/current_project/db_enabled fields
- Fix URL encoding: percent-encode project/file names in API URLs
- Fix import_json_file crash on re-import: upsert instead of insert
- Fix dual DB instances: share single ProjectDB between UI and API routes
- Also fixes top_level metadata never being updated on existing data_files

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tab_batch_ng.py

@@ -457,7 +457,7 @@ def _render_sequence_card(i, seq, batch_list, data, file_path, state,
 
         # --- VACE Settings (full width) ---
         with ui.expansion('VACE Settings', icon='settings').classes('w-full'):
-            _render_vace_settings(i, seq, batch_list, data, file_path, refresh_list)
+            _render_vace_settings(i, seq, batch_list, data, file_path, state, refresh_list)
 
         # --- LoRA Settings ---
         with ui.expansion('LoRA Settings', icon='style').classes('w-full'):
@@ -539,7 +539,7 @@ def _render_sequence_card(i, seq, batch_list, data, file_path, state,
 # VACE Settings sub-section
 # ======================================================================
 
-def _render_vace_settings(i, seq, batch_list, data, file_path, refresh_list):
+def _render_vace_settings(i, seq, batch_list, data, file_path, state, refresh_list):
     # VACE Schedule (needed early for both columns)
     sched_val = max(0, min(int(seq.get('vace schedule', 1)), len(VACE_MODES) - 1))