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/asset_pack.gd

@@ -0,0 +1,60 @@
+# AssetPack —— 把 Metin2 资源（assets/ + bgm/ + asset_index.txt 打成的 assets.zip）
+# 挂载到 res://，供 AssetRoot / C++ 的 FileAccess 读取。
+#
+# 桌面开发：仓库旁的散 assets/ 直接可用 -> ensure() 什么都不做。
+# 移动端：APK/IPA 里没有资源；assets.zip 由外部提供：
+#   Android —— adb push build/export/assets.zip /sdcard/Android/data/<pkg>/files/
+#   iOS     —— ios-deploy --upload assets.zip --to Documents/
+# 找到就 ProjectSettings.load_resource_pack() 挂到 res://。
+#
+# 候选路径：MT_ASSETS_ZIP 环境变量 -> user://assets.zip ->
+#           <可执行文件目录>/assets.zip -> res://../assets.zip（开发）
+#
+# FUTURE（下载版）：_find_local_zip() 失败时，改为 HTTPRequest 从 ASSET_PACK_URL
+# 下载到 user://assets.zip（断点续传 + sha256 校验 + 进度 UI），再走同一个 mount。
+class_name AssetPack
+extends RefCounted
+
+const ZIP_NAME := "assets.zip"
+# const ASSET_PACK_URL := ""   # FUTURE: 下载版填这里
+
+static var mounted := false
+static var last_source := ""
+
+# 返回 true = 资源可用（散文件 或 已挂载 zip）。同步；本地文件场景不阻塞。
+# force_zip=true：即使散 assets/ 可用也去挂 zip（测试 / 验证移动端路径用）。
+static func ensure(force_zip := false) -> bool:
+	if mounted:
+		return true
+	if not force_zip and AssetRoot.available():   # 散 assets/（桌面开发）
+		return true
+	var zip := _find_local_zip()
+	if zip == "":
+		# FUTURE: 这里改成下载 ASSET_PACK_URL -> user://assets.zip -> 继续
+		push_warning("[AssetPack] 找不到 %s（Android: adb push 到 files/；iOS: 上传到 Documents/）" % ZIP_NAME)
+		return false
+	if ProjectSettings.load_resource_pack(zip, false):
+		mounted = true
+		last_source = zip
+		print("[AssetPack] mounted ", zip)
+		return true
+	push_warning("[AssetPack] load_resource_pack 失败: " + zip)
+	return false
+
+static func _find_local_zip() -> String:
+	var cands: Array[String] = []
+	var env := OS.get_environment("MT_ASSETS_ZIP")
+	if env != "":
+		cands.append(env)
+	cands.append("user://" + ZIP_NAME)
+	var data_dir := OS.get_user_data_dir()
+	if data_dir != "":
+		cands.append(data_dir.path_join(ZIP_NAME))
+	var exe := OS.get_executable_path()
+	if exe != "":
+		cands.append(exe.get_base_dir().path_join(ZIP_NAME))
+	cands.append("res://../" + ZIP_NAME)   # 开发：仓库根旁
+	for c in cands:
+		if FileAccess.file_exists(c):
+			return c
+	return ""