feat(MNG): FCM 채널명 동기화 및 config 일원화 (7채널)

- push_urgent → push_vendor_register (거래처등록)
- push_payment → push_approval_request (결재요청)
- push_income 신규 추가 (입금)
- config/fcm.php 전체 7개 채널 등록
- FcmController validation 및 Blade select 옵션 반영

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/Http/Controllers/FcmController.php

@@ -99,7 +99,7 @@ public function sendPush(Request $request): View
             'tenant_id' => 'nullable|integer|exists:tenants,id',
             'user_id' => 'nullable|integer',
             'platform' => 'nullable|string|in:android,ios,web',
-            'channel_id' => 'nullable|string|in:push_default,push_urgent,push_payment,push_sales_order,push_purchase_order,push_contract',
+            'channel_id' => 'nullable|string|in:push_default,push_vendor_register,push_approval_request,push_income,push_sales_order,push_purchase_order,push_contract',
             'type' => 'nullable|string|max:50',
             'url' => 'nullable|string|max:500',
         ]);