Add support for per-department custom daily targets

- Introduced `department_daily_targets` field in criteria, renderer, and API to define daily target overrides for departments.
- Enhanced daily target logic to honor per-department overrides while maintaining backward compatibility.
- Updated SMS, email, and Slack renderers for consistent enforcement of text length limits with fallback to non-mbstring functions.
- Refactored order item update logic to improve database interaction safety by using setters.

openapi.yaml

@@ -8386,6 +8386,18 @@ components:
             For backward-compatibility the API also accepts camelCase `progressAlertTimeOfDay` on input.
           pattern: '^([01]\d|2[0-3]):[0-5]\d(?:Z|[+-](?:[01]\d|2[0-3]):?[0-5]\d)$'
           example: "14:30+02:00"
+        department_daily_targets:
+          type: object
+          description: |
+            Optional per-department custom daily targets. Keys are department IDs and values are non-negative integers representing the target per operating day for that department.
+            If omitted, the daily target is split evenly across selected departments. The canonical field name is snake_case `department_daily_targets`.
+            For backward-compatibility the API also accepts camelCase `departmentDailyTargets` on input.
+          additionalProperties:
+            type: integer
+            minimum: 0
+          example:
+            "12": 3
+            "15": 5
 
     DepartmentGoal:
       type: object