feat(server/pay): 订单列表端点 + 分币种展示价 + 富字段详情

- GET /v1/pay/orders 订单列表(Store.ListByUser,本地台账倒序)
- catalog 增 PriceUsdtMicro(USDT 一口价展示) + SettlementCurrency/DisplayAmountMinor
- 下单按支付方式落展示金额/结算币种(crypto→USDT / 法币→CNY),webhook 覆盖实际
- GetOrder 详情回带 sku/plan/method/amount/currency/created_at/paid_at
- 新增 List 越权/倒序/富字段 + 分币种展示金额 + 详情富字段测试
- 修 3 个 pre-existing 迁移测试(renumber 后 21→23 遗留)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013nMthbVEmQquxBRKb9Fj8u

server/internal/store/sqlite_migrate_test.go

@@ -29,8 +29,8 @@ func TestSQLiteMigrateUpDown(t *testing.T) {
 	if dirty {
 		t.Fatalf("schema dirty after MigrateUp")
 	}
-	if v != 21 {
-		t.Errorf("version = %d, want 21", v)
+	if v != 23 {
+		t.Errorf("version = %d, want 23", v)
 	}
 
 	// 2. Core tables exist.