feat(api): mobile API Milestone 1+2 — Sanctum auth + offline sync vertical slice

Milestone 1 (auth foundation):
- Installed laravel/sanctum; HasApiTokens on User; published config + migration.
- routes/api.php with /api/v1; Sanctum 'ability' middleware alias registered.
- AuthController: POST login (long-lived revocable device token w/ ability
  mobile-sync + devices table), GET me, POST logout. New Device model/table.

Milestone 2 (vertical slice, offline-first):
- progress_updates: +uuid (client-generated) +client_updated_at.
- ProjectApiController: GET projects (accessibleBy), GET projects/{id}/bundle
  (project/phases/layers/features, membership-authorized).
- SyncController: POST sync — batch ops, idempotent by uuid, per-op result
  (applied/duplicate/error), server-set user_id, authz by permission+membership.
  Currently handles progress_update.create.

Tests: tests/Feature/Api/MobileApiTest (9 passing) — auth, accessible projects,
bundle authz, sync apply+idempotency, permission enforcement.

Also fixed a latent schema bug: projects.reference (and external_reference_1)
existed in the live DB but had no migration — added a guarded migration so fresh
installs match production.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/Models/User.php

@@ -7,12 +7,13 @@ use Database\Factories\UserFactory;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Foundation\Auth\User as Authenticatable;
 use Illuminate\Notifications\Notifiable;
-use Spatie\Permission\Traits\HasRoles; 
+use Laravel\Sanctum\HasApiTokens;
+use Spatie\Permission\Traits\HasRoles;
 
 class User extends Authenticatable
 {
     /** @use HasFactory<UserFactory> */
-    use HasFactory, Notifiable, HasRoles;
+    use HasFactory, Notifiable, HasRoles, HasApiTokens;
 
     /**
      * The attributes that are mass assignable.