feat: uuid ids everywhere, pickers for linked tickets, @pi/ui checkboxes

- Postgres: every table has a uuid `id` (gen_random_uuid()); the event
  store keeps its relay order in `seq`, and the lookup tables their
  uniqueness in constraints of their own.
- MongoDB: `_id` is Mongo's ObjectId; `id` is the domain id (the same
  uuid as the aggregate's stream in Postgres), unique, and every query
  goes by it. Production starts from empty databases.
- Web: linking tickets and hanging one from a parent are picked from a
  searchable select (links across projects, parents within the project)
  instead of typing a key; every checkbox is @pi/ui's pi-checkbox.

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

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

@@ -16,7 +16,7 @@ import {
   untracked,
 } from '@angular/core';
 import { NgTemplateOutlet } from '@angular/common';
-import { PiIconComponent, PiNoteComponent } from '@pi/ui';
+import { PiCheckboxComponent, PiIconComponent, PiNoteComponent } from '@pi/ui';
 import { GitIntegrationComponent } from '../ui/git-integration';
 import { WebhooksComponent } from '../ui/webhooks';
 import { TransferComponent } from '../ui/transfer';
@@ -57,6 +57,7 @@ function idFrom(name: string): string {
   selector: 'ts-settings-page',
   changeDetection: ChangeDetectionStrategy.OnPush,
   imports: [
+    PiCheckboxComponent,
     RouterLink,
     GitIntegrationComponent,
     WebhooksComponent,
@@ -263,18 +264,16 @@ function idFrom(name: string): string {
                       })
                     "
                   />
-                  <label class="ts-check">
-                    <input
-                      type="checkbox"
-                      [checked]="status.requiresReason"
-                      (change)="
-                        edit('statuses', i, {
-                          requiresReason: $any($event.target).checked,
-                        })
-                      "
-                    />
-                    <span class="visually-hidden">Pide motivo</span>
-                  </label>
+                  <pi-checkbox
+                    class="ts-check"
+                    [checked]="status.requiresReason"
+                    (checkedChange)="
+                      edit('statuses', i, { requiresReason: $event })
+                    "
+                    ><span class="visually-hidden"
+                      >Pide motivo</span
+                    ></pi-checkbox
+                  >
                   <ng-container
                     [ngTemplateOutlet]="archive"
                     [ngTemplateOutletContext]="{
@@ -330,18 +329,15 @@ function idFrom(name: string): string {
                       @for (to of activeStatuses(); track to.id) {
                         <td>
                           @if (from.id !== to.id) {
-                            <input
-                              type="checkbox"
-                              [attr.aria-label]="from.name + ' → ' + to.name"
+                            <pi-checkbox
                               [checked]="allows(from.id, to.id)"
-                              (change)="
-                                toggleTransition(
-                                  from.id,
-                                  to.id,
-                                  $any($event.target).checked
-                                )
+                              (checkedChange)="
+                                toggleTransition(from.id, to.id, $event)
                               "
-                            />
+                              ><span class="visually-hidden"
+                                >{{ from.name }} → {{ to.name }}</span
+                              ></pi-checkbox
+                            >
                           }
                         </td>
                       }