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>

libs/api/tracker/presenters/src/lib/common/settings.ts

@@ -27,6 +27,8 @@ export interface SettingsPayload {
     template?: { description?: string | null; checklist?: string[] } | null;
   }[];
   areas: { id: string; name: string; archived: boolean }[];
+  /** Definition of done. Absent when saving: unchanged. */
+  checklistBeforeDone?: boolean;
   /** Absent when saving: unchanged. */
   customFields?: {
     id: string;
@@ -41,6 +43,7 @@ export function toSettingsPayload(settings: ProjectSettings): SettingsPayload {
   return {
     ...settings,
     customFields: settings.customFields ?? [],
+    checklistBeforeDone: !!settings.checklistBeforeDone,
     transitions: settings.statuses.map((s) => ({
       from: s.id,
       to: settings.transitions[s.id] ?? [],
@@ -72,6 +75,9 @@ export function fromSettingsPayload(payload: SettingsPayload): ProjectSettings {
         : {}),
     })),
     areas: payload.areas,
+    ...(payload.checklistBeforeDone != null
+      ? { checklistBeforeDone: payload.checklistBeforeDone }
+      : {}),
     ...(payload.customFields
       ? {
           customFields: payload.customFields.map((f) => ({