feat: add admin panel with multi-chain support and notification system

- Add full admin REST API: auth, API keys, chains, chain tokens, wallets,
  orders, RPC nodes, settings, dashboard stats, notifications
- Add JWT-based admin authentication and API key auth middleware
- Add multi-chain listeners: BSC, ETH, Polygon, Plasma, EVM WebSocket
- Add RPC node health check job with automatic failover
- Add Telegram notification channel for order events
- Add installer for first-run database initialization
- Add new DB models: admin_user, api_key, chain, chain_token,
  rpc_node, settings, notification_channel
- Add order statistics aggregation (daily/monthly/by-chain)
- Serve built admin SPA from embedded www/ assets
- Add comprehensive test coverage for all new features

src/model/data/chain_token_data.go

@@ -0,0 +1,125 @@
+package data
+
+import (
+	"strings"
+
+	"github.com/assimon/luuu/model/dao"
+	"github.com/assimon/luuu/model/mdb"
+)
+
+// ListEnabledChainTokens returns enabled tokens, optionally filtered by network.
+// An empty network returns all enabled tokens across all networks.
+func ListEnabledChainTokens(network string) ([]mdb.ChainToken, error) {
+	var rows []mdb.ChainToken
+	tx := dao.Mdb.Model(&mdb.ChainToken{}).Where("enabled = ?", true)
+	if n := strings.ToLower(strings.TrimSpace(network)); n != "" {
+		tx = tx.Where("network = ?", n)
+	}
+	err := tx.Order("network ASC, id ASC").Find(&rows).Error
+	return rows, err
+}
+
+// ListChainTokens returns rows optionally filtered by network.
+func ListChainTokens(network string) ([]mdb.ChainToken, error) {
+	var rows []mdb.ChainToken
+	tx := dao.Mdb.Model(&mdb.ChainToken{})
+	if network != "" {
+		tx = tx.Where("network = ?", strings.ToLower(network))
+	}
+	err := tx.Order("id ASC").Find(&rows).Error
+	return rows, err
+}
+
+// ListEnabledChainTokensByNetwork returns the enabled tokens for a network.
+// Scanners call this to learn which contract addresses to subscribe to.
+func ListEnabledChainTokensByNetwork(network string) ([]mdb.ChainToken, error) {
+	var rows []mdb.ChainToken
+	err := dao.Mdb.Model(&mdb.ChainToken{}).
+		Where("network = ?", strings.ToLower(network)).
+		Where("enabled = ?", true).
+		Find(&rows).Error
+	return rows, err
+}
+
+// GetEnabledChainTokenByContract finds one enabled token by (network,
+// contract_address). Used by EVM/TRON scanners to resolve the symbol
+// and decimals of an incoming transfer. Returns (zero row, nil) if no
+// match. The contract address match is case-insensitive.
+func GetEnabledChainTokenByContract(network, contractAddress string) (*mdb.ChainToken, error) {
+	row := new(mdb.ChainToken)
+	addr := strings.TrimSpace(contractAddress)
+	if addr == "" {
+		return row, nil
+	}
+	err := dao.Mdb.Model(row).
+		Where("network = ?", strings.ToLower(strings.TrimSpace(network))).
+		Where("enabled = ?", true).
+		Where("LOWER(contract_address) = ?", strings.ToLower(addr)).
+		Limit(1).Find(row).Error
+	return row, err
+}
+
+// GetEnabledChainTokenBySymbol finds one enabled token by (network, symbol).
+// Used by Solana native-SOL path where there's no contract address.
+func GetEnabledChainTokenBySymbol(network, symbol string) (*mdb.ChainToken, error) {
+	row := new(mdb.ChainToken)
+	sym := strings.TrimSpace(symbol)
+	if sym == "" {
+		return row, nil
+	}
+	err := dao.Mdb.Model(row).
+		Where("network = ?", strings.ToLower(strings.TrimSpace(network))).
+		Where("enabled = ?", true).
+		Where("UPPER(symbol) = ?", strings.ToUpper(sym)).
+		Limit(1).Find(row).Error
+	return row, err
+}
+
+// GetChainTokenByID fetches by primary key.
+func GetChainTokenByID(id uint64) (*mdb.ChainToken, error) {
+	row := new(mdb.ChainToken)
+	err := dao.Mdb.Model(row).Limit(1).Find(row, id).Error
+	return row, err
+}
+
+// CreateChainToken inserts a row.
+// If a soft-deleted row with the same (network, symbol) exists it is
+// restored with the incoming field values rather than creating a duplicate
+// that would violate the unique index.
+func CreateChainToken(row *mdb.ChainToken) error {
+	deleted := new(mdb.ChainToken)
+	err := dao.Mdb.Unscoped().
+		Where("network = ? AND symbol = ? AND deleted_at IS NOT NULL", row.Network, row.Symbol).
+		Limit(1).Find(deleted).Error
+	if err != nil {
+		return err
+	}
+	if deleted.ID > 0 {
+		err = dao.Mdb.Unscoped().Model(deleted).Updates(map[string]interface{}{
+			"deleted_at":       nil,
+			"contract_address": row.ContractAddress,
+			"decimals":         row.Decimals,
+			"enabled":          row.Enabled,
+			"min_amount":       row.MinAmount,
+		}).Error
+		if err != nil {
+			return err
+		}
+		row.ID = deleted.ID
+		return nil
+	}
+	return dao.Mdb.Create(row).Error
+}
+
+// UpdateChainTokenFields patches mutable columns.
+func UpdateChainTokenFields(id uint64, fields map[string]interface{}) error {
+	if len(fields) == 0 {
+		return nil
+	}
+	return dao.Mdb.Model(&mdb.ChainToken{}).Where("id = ?", id).Updates(fields).Error
+}
+
+// DeleteChainTokenByID soft-deletes the row.
+func DeleteChainTokenByID(id uint64) error {
+	return dao.Mdb.Where("id = ?", id).Delete(&mdb.ChainToken{}).Error
+}