Mini API: avatar, wallet payout/withdraw, stale-payment auto-cancel.

Adds account avatar upload (multipart proxy to identity), wallet payout-account
+ withdrawal endpoints, and a hourly mini:cancel-stale-payments command that
cancels payments pending beyond 6h (new MiniPayment::STATUS_CANCELED).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/Models/MiniPayment.php

@@ -10,6 +10,10 @@ class MiniPayment extends Model
     public const STATUS_PENDING = 'pending';
     public const STATUS_PAID = 'paid';
     public const STATUS_FAILED = 'failed';
+    public const STATUS_CANCELED = 'canceled';
+
+    /** Pending payments are auto-canceled after this many hours. */
+    public const STALE_PENDING_HOURS = 6;
 
     /** Platform fee on trader payments (Ladill Mini tier). */
     public const PLATFORM_FEE_RATE = 0.05;