Metin2 game client (P0–P11) + mobile asset pipeline

Networked client on the existing Godot 4.7 + libgr2 renderer:
- net: m2dev wire protocol (libsodium KX + XChaCha20), auth/select/game
  phases, EntityStore world model, ~all GC/CG headers. char create/delete,
  private shop / mall / cube, SHOP_GC_START_EX, guild, party (+ CG_PARTY_SET_STATE),
  quests, dragon soul, refine, safebox, exchange.
- UI: in-game windows migrated 1:1 from the reference uiscript/root .py —
  char status (/stat), inventory+equipment, select-item ([SELECT_ITEM] quest
  token), system-option + game-option + ESC system menu, private-shop 39-grid,
  party info board, shop tabs, atlas, minimap, quickbar, chat, …
- EterGrnLib polish: GR2 material blend/two-sided, LOD crossfade, motion-event
  dispatch, contact shadow, ray-AABB picking, weapon grip pre-transform.

Portable asset IO (A1) — all extension/libgr2/formats/mtproto reads routed
through godot::FileAccess (res:// PCK works on iOS/Android); standalone-lib
*_path() kept for the non-Godot CTests. AssetResolver + PropertyRegistry
switched to a baked index (bake_asset_index.gd) instead of std::filesystem.

Mobile builds: build-{android,ios}.sh, export-android.sh, pack-assets.sh,
gen-debug-keystore.sh. Assets ship as a zip mounted at runtime by
project/asset_pack.gd (adb push now; HTTP download is a drop-in later).

ctest 10/10, 34 GDScript suites, macOS/iOS/Android all build.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013EJxkHiNKS4kybHS3XKyAJ

project/client_main.gd

@@ -0,0 +1,19 @@
+# client_main —— 打包客户端的入口场景根（main_scene = res://client_main.tscn）。
+#
+# 只做一件事：起 AppFlow（登录 → 选人 → 进游戏 串场控制器）。
+# 资源目录由 AssetRoot 决定：默认 res://../assets（开发树），打包后设环境变量
+# MT_ASSETS 指向真实资源目录即可（见 project/asset_root.gd）。
+extends Node
+
+const AppFlow = preload("res://app_flow.gd")
+
+func _ready() -> void:
+	# 移动端：APK/IPA 里没有资源 —— 挂载外部的 assets.zip（adb push / ios-deploy 上传）。
+	AssetPack.ensure()
+	var root := AssetRoot.path()
+	if not AssetRoot.available():
+		push_warning("[client] 资源目录不存在：%s —— MT_ASSETS 环境变量 / assets.zip（adb push 到 files/）" % root)
+	var af := AppFlow.new()
+	af.name = "AppFlow"
+	add_child(af)
+	af.start(root)