feat: BindSentryContext middleware + queue job attempt tagging

WS-7 PR-2 commit 2.

- app/Http/Middleware/BindSentryContext.php: sets RFC §3.6 tags on the
  active Sentry scope (app, http.method, route_name, actor_type,
  user_id, organisation_id, event_id, impersonation). Multi-tenant
  invariant: throws RuntimeException in local/testing when an auth
  request to a tenant-scoped route lacks organisation_id; logs a
  warning in production so the user flow still completes.
- app/Listeners/Observability/TagJobAttemptOnSentry.php: tags
  queue.attempt on the scope from the JobProcessing event. Default
  stack-trace grouping preserved per §3.11.
- ActorType: VOLUNTEER case reserved for a future role split. Current
  resolver maps non-admin authenticated users to ORG_MEMBER.
- bootstrap/app.php: registers sentry.context alias. Applied inside
  auth:sanctum groups in routes/api.php so it runs after auth.
- AppServiceProvider::boot registers the queue listener.

Test count: 1507 to 1523. Larastan clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

api/app/Enums/Observability/ActorType.php

@@ -15,9 +15,13 @@ use Illuminate\Http\Request;
  *  1. Portal-token request → PORTAL_TOKEN
  *  2. Authenticated super_admin → SUPER_ADMIN
  *  3. Authenticated org_admin → ORGANIZER_ADMIN
- *  4. Authenticated volunteer (role match) → VOLUNTEER
- *  5. Other authenticated user → ORG_MEMBER
- *  6. None of the above → UNAUTHENTICATED
+ *  4. Other authenticated user → ORG_MEMBER (covers volunteers — Crewli has
+ *     no `volunteer` Spatie role today; volunteers join an organisation as
+ *     org_member with org-pivot semantics. Promote to a dedicated case once
+ *     the role model differentiates them at the user level.)
+ *  5. None of the above → UNAUTHENTICATED
+ *
+ * The VOLUNTEER case is reserved for that future split.
  */
 enum ActorType: string
 {
@@ -46,10 +50,6 @@ enum ActorType: string
             return self::ORGANIZER_ADMIN;
         }
 
-        if ($user->hasRole('volunteer')) {
-            return self::VOLUNTEER;
-        }
-
         return self::ORG_MEMBER;
     }
 }