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/web/tracker/presenters/src/lib/pages/settings.page.ts

@@ -530,6 +530,33 @@ function idFrom(name: string): string {
               </ol>
             </section>
 
+            <!-- Definition of done -->
+            <section class="ts-panel ts-block" aria-labelledby="dod-title">
+              <header class="ts-block__head">
+                <div>
+                  <h3 id="dod-title">Definición de «Hecho»</h3>
+                  <p class="ts-muted">
+                    Un ticket no pasa a un estado «Hecho» con su checklist a
+                    medias. El propietario y los admins sí pueden cerrarlo.
+                  </p>
+                </div>
+                <label class="ts-switch">
+                  <input
+                    type="checkbox"
+                    role="switch"
+                    [checked]="!!d.checklistBeforeDone"
+                    (change)="
+                      setChecklistBeforeDone($any($event.target).checked)
+                    "
+                  />
+                  <span class="ts-switch__track" aria-hidden="true"></span>
+                  <span>{{
+                    d.checklistBeforeDone ? 'Activada' : 'Desactivada'
+                  }}</span>
+                </label>
+              </header>
+            </section>
+
             <!-- Custom fields -->
             <section class="ts-panel ts-block" aria-labelledby="cf-title">
               <header class="ts-block__head">
@@ -1396,6 +1423,12 @@ export class SettingsPage {
     );
   }
 
+  protected setChecklistBeforeDone(on: boolean): void {
+    this.patch((d) => {
+      d.checklistBeforeDone = on;
+    });
+  }
+
   protected addField(): void {
     this.patch((d) =>
       d.customFields.push({