feat(fc2b): add /api/allowlist and /api/aliases endpoints

Allowlist: list-all, get-one (404 if not listed), PATCH threshold
(range-validated), DELETE. Aliases: list-all (with canonical name),
create (idempotent, 201), DELETE by (string, category). Tests
integration-marked.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/api/__init__.py

@@ -14,6 +14,8 @@ api_bp.add_url_rule("/health", view_func=health.get_health, methods=["GET"])
 
 
 def all_blueprints() -> list[Blueprint]:
+    from .aliases import aliases_bp
+    from .allowlist import allowlist_bp
     from .gallery import gallery_bp
     from .import_admin import import_admin_bp
     from .settings import settings_bp
@@ -26,4 +28,6 @@ def all_blueprints() -> list[Blueprint]:
         settings_bp,
         import_admin_bp,
         suggestions_bp,
+        allowlist_bp,
+        aliases_bp,
     ]