refactor(config): eliminate ErupeConfig global variable

Replace the mutable global `_config.ErupeConfig` with dependency
injection across 79 files. Config is now threaded through existing
paths: `ClientContext.RealClientMode` for packet encoding, `s.server.
erupeConfig` for channel handlers, and explicit parameters for utility
functions. This removes hidden coupling, enables test parallelism
without global save/restore, and prevents low-level packages from
reaching up to the config layer.

Key changes:
- Enrich ClientContext with RealClientMode for packet files
- Add mode parameter to CryptConn, mhfitem, mhfcourse functions
- Convert handlers_commands init() to lazy sync.Once initialization
- Delete global var, init(), and helper functions from config.go
- Update all tests to pass config explicitly

server/channelserver/handlers_shop_gacha_test.go

@@ -4,13 +4,14 @@ import (
 	"testing"
 
 	"erupe-ce/common/byteframe"
+	_config "erupe-ce/config"
 )
 
 func TestWriteShopItems_Empty(t *testing.T) {
 	bf := byteframe.NewByteFrame()
 	items := []ShopItem{}
 
-	writeShopItems(bf, items)
+	writeShopItems(bf, items, _config.ZZ)
 
 	result := byteframe.NewByteFrameFromBytes(bf.Data())
 	count1 := result.ReadUint16()
@@ -43,7 +44,7 @@ func TestWriteShopItems_SingleItem(t *testing.T) {
 		},
 	}
 
-	writeShopItems(bf, items)
+	writeShopItems(bf, items, _config.ZZ)
 
 	result := byteframe.NewByteFrameFromBytes(bf.Data())
 	count1 := result.ReadUint16()
@@ -117,7 +118,7 @@ func TestWriteShopItems_MultipleItems(t *testing.T) {
 		{ID: 3, ItemID: 300, Cost: 2000, Quantity: 1},
 	}
 
-	writeShopItems(bf, items)
+	writeShopItems(bf, items, _config.ZZ)
 
 	result := byteframe.NewByteFrameFromBytes(bf.Data())
 	count1 := result.ReadUint16()