feat(wallet): migrate to backend API

lib/api/transactions.ts

@@ -1,5 +1,58 @@
-import { useWalletStore } from "@/store/wallet"
+import type { WalletTransaction } from "@/lib/types"
 
-export function listTransactions() {
-  return useWalletStore.getState().transactions
+import { httpJson } from "./http"
+
+type Paginated<T> = {
+  items: T[]
+  meta: {
+    total: number
+    offset: number
+    limit: number
+  }
+}
+
+export type ListWalletTransactionsOptions = {
+  offset?: number
+  limit?: number
+}
+
+function withOffsetLimit(path: string, options?: ListWalletTransactionsOptions): string {
+  const offset = options?.offset ?? 0
+  const limit = options?.limit ?? 1000
+  const searchParams = new URLSearchParams({
+    offset: String(offset),
+    limit: String(limit),
+  })
+  return `${path}?${searchParams.toString()}`
+}
+
+function unwrapWalletBalance(value: unknown): number | undefined {
+  if (typeof value === "number") return value
+  if (typeof value !== "object" || value === null) return undefined
+
+  const v = value as { balance?: unknown; amount?: unknown }
+  if (typeof v.balance === "number") return v.balance
+  if (typeof v.amount === "number") return v.amount
+  return undefined
+}
+
+export async function getWalletBalance(): Promise<number> {
+  const res = await httpJson<unknown>("/api/v1/wallet/balance", { cache: "no-store" })
+  const balance = unwrapWalletBalance(res)
+  if (balance === undefined) {
+    throw new Error("Invalid wallet balance response")
+  }
+  return balance
+}
+
+export async function listWalletTransactions(
+  options?: ListWalletTransactionsOptions,
+): Promise<WalletTransaction[]> {
+  const res = await httpJson<Paginated<WalletTransaction>>(
+    withOffsetLimit("/api/v1/wallet/transactions", options),
+    {
+      cache: "no-store",
+    },
+  )
+  return res.items
 }