fix: address code review feedback - round 2

- Reject path separators (/, \, os.sep) in tag components for defense-in-depth
- Add comment explaining double-relpath normalization trick
- Add _require_assets_feature_enabled decorator returning 503 when disabled
- Call asset_seeder.disable() when --enable-assets is not passed
- Add iter_chunks to bulk_update_needs_verify, bulk_update_is_missing,
  and delete_references_by_ids to respect SQLite bind param limits
- Fix CacheStateRow.size_bytes NULL coercion (0 -> None) to avoid
  false needs_verify flags on assets with unknown size
- Add PermissionError catch in delete_asset_tags route (403 vs 500)
- Add hash-is-None guard in delete_orphaned_seed_asset
- Validate from_asset_id in reassign_asset_references
- Initialize _prune_first in __init__, remove getattr workaround
- Cap error accumulation in _add_error to 200
- Remove confirmed dead code: seed_assets, compute_filename_for_asset,
  ALLOWED_ROOTS, AssetNotFoundError, SetTagsResult, update_enrichment_level,
  Asset.to_dict, AssetReference.to_dict, _AssetSeeder.enable

Amp-Thread-ID: https://ampcode.com/threads/T-019cb610-1b55-74b6-8dbb-381d73c387c0
Co-authored-by: Amp <amp@ampcode.com>

app/assets/services/path_utils.py

@@ -3,8 +3,7 @@ from pathlib import Path
 from typing import Literal
 
 import folder_paths
-from app.assets.database.queries import list_references_by_asset_id
-from app.assets.helpers import normalize_tags, select_best_live_path
+from app.assets.helpers import normalize_tags
 
 
 _NON_MODEL_FOLDER_NAMES = frozenset({"custom_nodes"})
@@ -161,14 +160,6 @@ def compute_filename_for_reference(session, ref) -> str | None:
     return None
 
 
-def compute_filename_for_asset(session, asset_id: str) -> str | None:
-    """Compute the relative filename for an asset from its best live reference path."""
-    primary_path = select_best_live_path(
-        list_references_by_asset_id(session, asset_id=asset_id)
-    )
-    return compute_relative_filename(primary_path) if primary_path else None
-
-
 def get_name_and_tags_from_asset_path(file_path: str) -> tuple[str, list[str]]:
     """Return (name, tags) derived from a filesystem path.