The server's ReadTimeout (15s) was closing SSE connections shortly after
they were established, causing a rapid connect/disconnect loop. The handler
already disabled WriteTimeout but not ReadTimeout.
- Add source badges (assembly=teal, manual=blue) to BOM display rows
- Add info banner when assembly-sourced entries exist
- Change source input from text field to select dropdown
- Add merge response types to types.ts
Closes#47
Add file_count and files_total_size to item API responses, computed
via batch query on item_files table (no migration needed).
- Add BatchGetFileStats() to audit_queries.go (follows BatchCheckBOM pattern)
- Add file stats to ItemResponse, HandleListItems, HandleGetItem, HandleGetItemByUUID
- Add 'Files' column to ItemTable (default visible in vertical mode)
- Add has_files computed field to audit completeness scoring (weight 1 for manufactured)
