feat: definition of done per project

A project can ask that tickets reach a DONE status only with their
checklist ticked (settings.checklistBeforeDone, off by default; absent
when saving means unchanged). Members get a 422 telling how many steps are
left; owners and admins may still close it. Settings has the switch and
the ticket's checklist says when the project asks for it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/api/openapi.json

@@ -10982,6 +10982,10 @@
             "items": {
               "$ref": "#/components/schemas/CustomFieldDefinitionDto"
             }
+          },
+          "checklistBeforeDone": {
+            "type": "boolean",
+            "description": "Definition of done: tickets reach DONE only with their checklist ticked"
           }
         },
         "required": [
@@ -10989,7 +10993,8 @@
           "transitions",
           "issueTypes",
           "areas",
-          "customFields"
+          "customFields",
+          "checklistBeforeDone"
         ]
       },
       "ProjectDto": {
@@ -11379,6 +11384,10 @@
             "items": {
               "$ref": "#/components/schemas/CustomFieldDefinitionBodyDto"
             }
+          },
+          "checklistBeforeDone": {
+            "type": "boolean",
+            "description": "Definition of done: tickets reach a DONE status only with their checklist ticked (owners and admins may override). Absent: unchanged"
           }
         },
         "required": [