refactor: db-only credits and admin controls

Remove blockchain dependence from credit flow:
- watch credits now DB-only
- webhook earnings now DB-only
- wallet balance now DB-only
- admin bonus/adjustment routes operate on DB totals

Add admin adjustment API for account control.
Keep Solana service file unused for now; safe to delete later.

frontend/src/lib/api.ts

@@ -87,6 +87,8 @@ export const adminApi = {
 	updateUser: (id: string, data: any) => api.put(`/admin/users/${id}`, data),
 	grantBonus: (userId: string, amount: number, reason?: string) =>
 		api.post(`/admin/users/${userId}/bonus`, { amount, reason }),
+	adjustUser: (userId: string, amount: number, reason?: string) =>
+		api.post(`/wallet/admin/${userId}/adjust`, { amount, reason }),
 	getAnalytics: () => api.get("/admin/analytics"),
 	getAllTransactions: (page = 1, limit = 50) =>
 		api.get(`/transactions/admin/all?page=${page}&limit=${limit}`),