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/export_presets.cfg

@@ -59,3 +59,70 @@ privacy/downloads_folder_usage_description=""
 privacy/network_volumes_usage_description=""
 privacy/removable_volumes_usage_description=""
 ssh_remote_deploy/enabled=false
+
+[preset.1]
+
+name="Android"
+platform="Android"
+runnable=true
+advanced_options=false
+dedicated_server=false
+custom_features=""
+export_filter="all_resources"
+include_filter=""
+exclude_filter=""
+export_path="../build/export/mtgodot-poc.apk"
+patches=PackedStringArray()
+encryption_include_filters=""
+encryption_exclude_filters=""
+seed=0
+encrypt_pck=false
+encrypt_directory=false
+script_export_mode=2
+
+[preset.1.options]
+
+custom_template/debug=""
+custom_template/release=""
+gradle_build/use_gradle_build=true
+gradle_build/gradle_build_directory="res://android"
+gradle_build/android_source_template=""
+gradle_build/compress_native_libraries=false
+gradle_build/export_format=0
+gradle_build/min_sdk=""
+gradle_build/target_sdk=""
+architectures/armeabi-v7a=false
+architectures/arm64-v8a=true
+architectures/x86=false
+architectures/x86_64=false
+version/code=1
+version/name="1.0"
+package/unique_name="org.internal.mtgodotpoc"
+package/name=""
+package/signed=true
+package/app_category=2
+package/retain_data_on_uninstall=false
+package/exclude_from_recents=false
+package/show_in_android_tv=false
+package/show_in_app_library=true
+package/show_as_launcher_app=false
+launcher_icons/main_192x192=""
+launcher_icons/adaptive_foreground_432x432=""
+launcher_icons/adaptive_background_432x432=""
+launcher_icons/adaptive_monochrome_432x432=""
+graphics/opengl_debug=false
+xr_features/xr_mode=0
+screen/immersive_mode=true
+screen/support_small=true
+screen/support_normal=true
+screen/support_large=true
+screen/support_xlarge=true
+user_data_backup/allow=false
+command_line/extra_args=""
+apk_expansion/enable=false
+apk_expansion/SALT=""
+apk_expansion/public_key=""
+permissions/internet=true
+permissions/access_network_state=true
+permissions/access_wifi_state=true
+permissions/wake_lock=true