chore: remove legacy feature.py re-export

Feature is now only in app/modules/billing/models/ (canonical location).

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

models/database/feature.py

@@ -1,22 +0,0 @@
-# models/database/feature.py
-"""
-DEPRECATED: This module re-exports from the canonical location.
-
-Feature is now part of the billing module.
-Please update imports to use:
-    from app.modules.billing.models import Feature, FeatureCode, FeatureCategory, FeatureUILocation
-"""
-
-from app.modules.billing.models import (
-    Feature,
-    FeatureCategory,
-    FeatureCode,
-    FeatureUILocation,
-)
-
-__all__ = [
-    "Feature",
-    "FeatureCategory",
-    "FeatureCode",
-    "FeatureUILocation",
-]