fix: ruff linting errors and add comprehensive test coverage for asset queries

- Fix unused imports in routes.py, asset.py, manager.py, asset_management.py, ingest.py
- Fix whitespace issues in upload.py, asset_info.py, ingest.py
- Fix typo in manager.py (stray character after result["asset"])
- Fix broken import in test_metadata.py (project_kv moved to asset_info.py)
- Add fixture override in queries/conftest.py for unit test isolation

Add 48 new tests covering all previously untested query functions:
- asset.py: upsert_asset, bulk_insert_assets
- cache_state.py: upsert_cache_state, delete_cache_states_outside_prefixes,
  get_orphaned_seed_asset_ids, delete_assets_by_ids, get_cache_states_for_prefixes,
  bulk_set_needs_verify, delete_cache_states_by_ids, delete_orphaned_seed_asset,
  bulk_insert_cache_states_ignore_conflicts, get_cache_states_by_paths_and_asset_ids
- asset_info.py: insert_asset_info, get_or_create_asset_info,
  update_asset_info_timestamps, replace_asset_info_metadata_projection,
  bulk_insert_asset_infos_ignore_conflicts, get_asset_info_ids_by_ids
- tags.py: bulk_insert_tags_and_meta

Total: 119 tests pass (up from 71)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/assets/database/queries/asset.py

@@ -1,4 +1,3 @@
-from typing import Iterable
 
 import sqlalchemy as sa
 from sqlalchemy import select

app/assets/database/queries/asset_info.py

@@ -1,7 +1,7 @@
 """
 Pure atomic database queries for AssetInfo operations.
 
-This module contains only atomic DB operations - no business logic, 
+This module contains only atomic DB operations - no business logic,
 no filesystem operations, no orchestration across multiple tables.
 """
 from collections import defaultdict
@@ -246,7 +246,7 @@ def get_or_create_asset_info(
     )
     if info:
         return info, True
-    
+
     existing = session.execute(
         select(AssetInfo)
         .where(