Refactor V3 CRUD: Extract schema introspection logic.

- Created app/lib_schema_v3.py to isolate database and Pydantic model introspection.
- Updated app/routers/api_crud_v3.py to use get_object_schema_info(), completing the modularization.
- Finalized refactoring plan documentation in documentation/REFACTOR_API_CRUD_V3.md.

app/routers/api_crud_v3.py

@@ -17,6 +17,7 @@ from app.lib_api_crud_v3 import (
     check_account_access, apply_forced_account_filter, filter_order_by,
     get_supported_filters, safe_json_loads, sanitize_payload
 )
+from app.lib_schema_v3 import get_object_schema_info
 from app.models.response_models import *
 from app.models.api_crud_models import SearchFilter, SearchQuery
 from app.ae_obj_types_def import obj_type_kv_li
@@ -66,43 +67,11 @@ async def get_obj_schema(
     
     This enables dynamic form generation without hardcoding schemas in the frontend.
     """
-    from app.db_sql import db
-    from sqlalchemy import text
-
-    if obj_type not in obj_type_kv_li:
-        return mk_resp(data=False, status_code=400, response=response, status_message=f"Object type '{obj_type}' not found.")
-
-    obj_cfg = obj_type_kv_li[obj_type]
-    table_name = obj_cfg.get(f'tbl_{view}', obj_cfg.get('tbl_default', obj_cfg.get('tbl')))
-    model_key = f'mdl_{variant}' if variant != 'base' else 'mdl'
-    model = obj_cfg.get(model_key, obj_cfg.get('mdl_default', obj_cfg.get('mdl')))
-
-    if not table_name:
-        return mk_resp(data=False, status_code=500, response=response, status_message=f"Table configuration for '{obj_type}' is missing.")
-
-    schema_info = {
-        "object_type": obj_type,
-        "view": view,
-        "variant": variant,
-        "database": {"table_name": table_name, "columns": []},
-        "model": {"name": model.__name__ if hasattr(model, '__name__') else str(model), "fields": {}}
-    }
-
-    try:
-        db_result = db.execute(text(f"DESCRIBE `{table_name}`"))
-        for row in db_result.fetchall():
-            schema_info["database"]["columns"].append({
-                "field": row[0], "type": row[1], "nullable": row[2] == 'YES',
-                "key": row[3], "default": row[4], "extra": row[5]
-            })
-    except Exception as e:
-        schema_info["database"]["error"] = str(e)
-
-    if model and hasattr(model, "__fields__"):
-        for field_name, field in model.__fields__.items():
-            field_info = {"alias": field.alias, "type": str(field.outer_type_), "required": field.required, "default": field.default}
-            if field.field_info.description: field_info["description"] = field.field_info.description
-            schema_info["model"]["fields"][field_name] = field_info
+    schema_info = get_object_schema_info(obj_type, view, variant)
+    
+    if "error" in schema_info:
+        status_code = 400 if "not found" in schema_info["error"] else 500
+        return mk_resp(data=False, status_code=status_code, response=response, status_message=schema_info["error"])
 
     return mk_resp(data=schema_info, response=response)