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

libgr2/CMakeLists.txt

@@ -0,0 +1,25 @@
+# libgr2 —— gr2 v6 只读读取器（M0）。零第三方依赖。
+add_library(libgr2 STATIC
+    src/gr2_file.cpp          # T1  header + section table + fixup
+    src/gr2_decompress.cpp    # T2  section 解压分派
+    src/oodle1.c              # T2  Granny Oodle1 解码（端口自泄露 SDK）
+    src/gr2_typetree.cpp      # T3  自描述类型树遍历
+    src/gr2_fileinfo.cpp      # T4  FileInfo 汇总
+    src/gr2_skeleton.cpp      # T5  骨架 + bind pose 自洽检查
+    src/gr2_mesh.cpp          # T6  顶点 / 索引 / 三角组 / BoneBindings
+    src/gr2_anim.cpp          # T7a/T7b  曲线分类 + 解码子集
+    src/gr2_material.cpp      # 材质视图（附加）：root.Materials → 贴图文件名
+)
+add_library(xrender::libgr2 ALIAS libgr2)
+
+target_include_directories(libgr2
+    PUBLIC  ${CMAKE_CURRENT_SOURCE_DIR}/include
+    PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/src)
+
+target_compile_features(libgr2 PUBLIC cxx_std_20)
+
+if(BUILD_TESTING)
+    add_executable(libgr2_loader_errors_test tests/loader_errors.cpp)
+    target_link_libraries(libgr2_loader_errors_test PRIVATE xrender::libgr2)
+    add_test(NAME libgr2.loader_errors COMMAND libgr2_loader_errors_test)
+endif()