feat: add Solana payment scanning with USDT/USDC support and wallet management API

- Rewrite Solana scanner: stateless scan with processed-signature cache, query wallet + USDT ATA + USDC ATA addresses to cover all SPL transfers
  - Add network field to transaction_lock (4-tuple unique index) and order flow
  - Add wallet management endpoints (add/list/get/status/delete) with token auth
  - Add network info to Telegram payment notification
  - Add USDC hint to test script GMPay prompt
  - Add API docs and Solana scanning docs

src/model/mdb/wallet_address_mdb.go

@@ -5,6 +5,11 @@ const (
 	TokenStatusDisable = 2
 )
 
+const (
+	NetworkTron   = "tron"
+	NetworkSolana = "solana"
+)
+
 type WalletAddress struct {
 	Network string `gorm:"column:network;uniqueIndex:wallet_address_network_address_uindex" json:"network"`
 	Address string `gorm:"column:address;uniqueIndex:wallet_address_network_address_uindex" json:"address"`