feat: archive a project instead of deleting it

The owner archives a finished project (archiveProject, POST
/projects/{project}/archive) and brings it back (unarchive). While
archived it stays readable, managers still read its rules and webhooks,
but no command changes it: contributing and managing checks refuse with
422, votes and public proposals too, and automations do not run. The web
shows a read-only notice on every page of it (with «Desarchivar» for the
owner), hides what edits, marks it on the home page and lists it last.

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

libs/web/tracker/presenters/src/lib/pages/project-shell.page.ts

@@ -101,12 +101,27 @@ import { projectTone, PUBLIC_TONE, ROLE } from '../ui/copy';
         <a routerLink="analytics" routerLinkActive="is-active">Estadísticas</a>
         <a routerLink="activity" routerLinkActive="is-active">Actividad</a>
         <a routerLink="members" routerLinkActive="is-active">Miembros</a>
-        @if (facade.canManage()) {
+        @if (facade.canManage() || facade.isOwner()) {
           <a routerLink="settings" routerLinkActive="is-active"
             >Configuración</a
           >
         }
       </nav>
+      @if (project.archivedAt) {
+        <p class="ts-archived" role="status">
+          <strong>Proyecto archivado</strong>
+          Se puede ver todo, pero es de solo lectura.
+          @if (facade.isOwner()) {
+            <button
+              type="button"
+              class="ts-plain-link"
+              (click)="facade.setArchived(false)"
+            >
+              Desarchivar
+            </button>
+          }
+        </p>
+      }
       <router-outlet />
     } @else if (facade.error(); as error) {
       <pi-note
@@ -142,6 +157,19 @@ import { projectTone, PUBLIC_TONE, ROLE } from '../ui/copy';
     }
   `,
   styles: `
+    .ts-archived {
+      display: flex;
+      align-items: baseline;
+      flex-wrap: wrap;
+      gap: 0.5rem;
+      margin: 0 0 1rem;
+      padding: 0.625rem 0.875rem;
+      border: 1px solid var(--ts-line);
+      border-radius: 0.625rem;
+      background: var(--ts-sunken);
+      color: var(--ts-ink-soft);
+      font-size: 0.875rem;
+    }
     .ts-eyebrow .ts-pill {
       margin-left: 0.5rem;
       letter-spacing: 0;