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/bin/mtgodot.gdextension

@@ -8,3 +8,29 @@ reloadable = true
 
 macos.debug = "res://bin/libmtgodot.macos.template_debug.dylib"
 macos.release = "res://bin/libmtgodot.macos.template_release.dylib"
+
+ios.debug = "res://bin/libmtgodot.ios.template_debug.a"
+ios.release = "res://bin/libmtgodot.ios.template_release.a"
+
+android.debug.arm64 = "res://bin/libmtgodot.android.template_debug.arm64.so"
+android.release.arm64 = "res://bin/libmtgodot.android.template_release.arm64.so"
+
+[dependencies]
+
+; iOS can't dlopen: the extension archive above is linked into the app at export
+; time, and it needs every static lib it was built against on the link line.
+; `./build-ios.sh` stages these into project/bin/ios/. See docs/PLATFORMS.md (F1).
+ios.debug = {
+    "res://bin/ios/libgodot-cpp.ios.template_debug.arm64.a" : "",
+    "res://bin/ios/liblibgr2.a" : "",
+    "res://bin/ios/libxr_formats.a" : "",
+    "res://bin/ios/libmtnet.a" : "",
+    "res://bin/ios/libsodium.a" : ""
+}
+ios.release = {
+    "res://bin/ios/libgodot-cpp.ios.template_release.arm64.a" : "",
+    "res://bin/ios/liblibgr2.a" : "",
+    "res://bin/ios/libxr_formats.a" : "",
+    "res://bin/ios/libmtnet.a" : "",
+    "res://bin/ios/libsodium.a" : ""
+}