security: round 3 — token security (crypto random, hashed storage, portal middleware)

Token generation:
- Replace Str::ulid() with bin2hex(random_bytes(32)) for 256-bit entropy
- Store SHA-256 hash in database, never plaintext tokens
- Hash input before lookup on all token endpoints

Invitation tokens:
- InvitationService: generate crypto random, store hash, pass plain
  token transiently for email URL via UserInvitation::$plainToken
- InvitationController show/accept: hash input before DB lookup
- AcceptInvitationRequest: hash token before invitation lookup
- Migration: widen user_invitations.token and artists.portal_token
  from char(26) to char(64) for SHA-256 hex digests

Portal token auth:
- PortalTokenController: remove Schema::hasTable() runtime checks,
  hash token before lookup, return shaped response via PortalEventResource
  instead of raw model data
- Create PortalEventResource (name, dates, status only — no internals)
- Handle missing production_requests table gracefully via try/catch

Portal token middleware:
- Implement full token validation: extract from Bearer header or ?token=
  query param, hash, look up in artists/production_requests, verify
  event exists and is not draft/closed, set portal context on request
- Return generic 401 on any failure (no information leakage)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/database/factories/UserInvitationFactory.php

@@ -8,7 +8,6 @@ use App\Models\Organisation;
 use App\Models\User;
 use App\Models\UserInvitation;
 use Illuminate\Database\Eloquent\Factories\Factory;
-use Illuminate\Support\Str;
 
 /** @extends Factory<UserInvitation> */
 final class UserInvitationFactory extends Factory
@@ -28,7 +27,11 @@ final class UserInvitationFactory extends Factory
             $invitation->invited_by_user_id ??= User::factory()->create()->id;
             $invitation->organisation_id ??= Organisation::factory()->create()->id;
             $invitation->role ??= 'org_member';
-            $invitation->token ??= strtolower((string) Str::ulid());
+            if ($invitation->token === null) {
+                $plainToken = bin2hex(random_bytes(32));
+                $invitation->token = hash('sha256', $plainToken);
+                $invitation->plainToken = $plainToken;
+            }
             $invitation->status ??= 'pending';
             $invitation->expires_at ??= now()->addDays(7);
         });