fix(crud): extend Vision ID safety net to all response paths

- Extracted apply_vision_id_fix() helper to lib_api_crud_v3.py — single
  source of truth for the fix that ensures {obj_type}_id in responses is
  always the random string, never the DB integer.
- Applied to all response-returning paths in api_crud_v3.py:
  GET single, GET list, POST search, POST create, PATCH update.
- Applied to all response-returning paths in api_crud_v3_nested.py:
  GET child list, POST search, POST create, GET single child, PATCH child.
- Removed duplicate get_child_obj and patch_child_obj route handlers in
  api_crud_v3_nested.py — FastAPI silently routes to only the first
  matching handler, so the second definitions were unreachable dead code.

Covers all 23 V3 CRUD models still using the old integer-alias pattern.
The archive_content model was already migrated to Vision IDs; this fix
ensures every other model gets correct responses without individual migration.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/lib_api_crud_v3.py

@@ -8,6 +8,19 @@ from app.models.error_models import StandardError
 
 log = logging.getLogger(__name__)
 
+def apply_vision_id_fix(resp_data: dict, obj_type: str, by_alias: bool) -> dict:
+    """
+    V3 contract: {obj_type}_id in responses must be the random string, never the DB integer.
+    Applies to models not yet migrated to the Vision ID pattern (root_validator).
+    Safe to call on already-migrated models — no-op if the value is already a string.
+    """
+    _id_key = f'{obj_type}_id' if by_alias else 'id'
+    _rand_key = f'{obj_type}_id_random' if by_alias else 'id_random'
+    if isinstance(resp_data.get(_id_key), int) and resp_data.get(_rand_key):
+        resp_data[_id_key] = resp_data[_rand_key]
+    return resp_data
+
+
 def format_db_error(raw_error: str) -> StandardError:
     """
     Parses raw SQLAlchemy/MariaDB errors into structured StandardError objects.