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

formats/splat.h

@@ -0,0 +1,30 @@
+// W2 —— tile.raw -> 每图层 258×258 alpha（splat 权重）。
+// 逐字节照 GameLib/AreaTerrain.cpp CTerrain::RAW_GenerateSplat：
+//   texel 值 = TextureSet 运行时图层索引；
+//   layer i 的 alpha = 0xFF 当 tile==i；当 tile>i 且 3×3 邻域有 ==i 时也 0xFF（1px 羽化）；否则 0。
+// SHINSOO §9-W2。无 godot 依赖。
+#pragma once
+#include <cstdint>
+#include <vector>
+
+#include "terrain_files.h"
+
+namespace fmt {
+
+constexpr int SPLAT_RAW_XY = TILEMAP_RAW_XY; // 258
+
+struct SplatLayer {
+    int layer = 0;                 // TextureSet 运行时索引（1..N）
+    std::vector<uint8_t> alpha;    // 258*258，行主序
+    int coverage = 0;              // alpha==0xFF 的 texel 数（调试 / 决定是否提交）
+};
+
+struct SplatSet {
+    std::vector<SplatLayer> layers;      // 只含在本区块出现过的图层，按索引升序
+    std::vector<int> tile_histogram;     // [runtime_layer_index] -> texel 数（长度 = max+1）
+};
+
+// tile 来自 load_tile_map。runtime_layer_count = TextureSet.runtime_count()（含 index 0 空层）。
+void build_splat(const TileMap& tile, int runtime_layer_count, SplatSet& out);
+
+} // namespace fmt