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/src/gr2_decompress.cpp

@@ -0,0 +1,58 @@
+// M0 T2 —— section 解压分派。见 docs/steps/M0-gr2-reader.md
+#include "internal.h"
+#include "oodle1.h"
+#include <cstring>
+
+namespace gr2 {
+
+// src 指向文件里该 section 的压缩字节（长度 s.data_size）。
+// 本函数会做一份可写的、尾部留 32B 零的副本（Oodle1 解码器会写它、读过界）。
+bool File::Impl::decompress_section(const detail::GrnSection& s, const uint8_t* src,
+                                    detail::Section& out, LoadError* err) {
+    out.info = {s.compression, s.data_size, s.expanded_data_size, s.pointer_fixup_count, 0};
+
+    if (s.expanded_data_size == 0) {           // 空 section
+        out.data.clear();
+        return true;
+    }
+
+    switch (s.compression) {
+    case 0: { // NoCompression
+        out.data.assign(src, src + s.data_size);
+        out.data.resize(s.expanded_data_size);
+        return true;
+    }
+    case 1:   // Oodle0 —— 同一族解码器的变体，暂未实现（T2 后续；样本里极少）
+        out.info.decompress_status = 1;
+        if (err) *err = {"section", "Oodle0 not implemented (M0 T2)"};
+        return false;
+    case 2: { // Oodle1
+        // 4 字节对齐的可写副本 + 32B 零尾
+        std::vector<uint8_t> buf;
+        buf.reserve(s.data_size + 32);
+        buf.assign(src, src + s.data_size);
+        buf.resize(s.data_size + 32, 0);
+        out.data.assign(s.expanded_data_size, 0);
+        int rc = gr2_oodle1_decompress(/*byte_reversed=*/0,
+                                       s.data_size, buf.data(),
+                                       s.first16bit, s.first8bit, s.expanded_data_size,
+                                       out.data.data());
+        out.info.decompress_status = rc;
+        if (rc != 0) {
+            if (err) *err = {"section", "Oodle1 decompress failed"};
+            return false;
+        }
+        return true;
+    }
+    case 4:   // BitKnit —— 无公开实现（全样本 0 个）
+        out.info.decompress_status = 4;
+        if (err) *err = {"section", "BitKnit unsupported (M0 T2)"};
+        return false;
+    default:
+        out.info.decompress_status = -1;
+        if (err) *err = {"section", "unknown compression format"};
+        return false;
+    }
+}
+
+} // namespace gr2