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

pack-assets.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+# Pack the Metin2 asset tree into build/export/assets.zip for the mobile builds.
+#
+# The APK/IPA is code-only (assets are gitignored and can't go in res://). The
+# zip is mounted at runtime by AssetPack.ensure() -> res://assets/... and read
+# through godot::FileAccess (all C++ asset IO now goes through it).
+#
+#   ./pack-assets.sh          # bake index + zip -0 (store, no compression)
+#
+# Deploy:
+#   Android:  adb push build/export/assets.zip /sdcard/Android/data/org.internal.mtgodotpoc/files/
+#   iOS:      ios-deploy --bundle_id org.internal.mtgodotpoc --upload build/export/assets.zip --to Documents/
+#   desktop:  not needed (loose assets/ is used directly)
+set -euo pipefail
+cd "$(dirname "$0")"
+
+GODOT="${GODOT:-godot}"
+OUT="build/export/assets.zip"
+
+if [ ! -d assets ]; then
+	echo "no ./assets — nothing to pack" >&2
+	exit 1
+fi
+
+# 1. refresh the AssetResolver index (baked; device can't std::filesystem-scan a pack)
+"$GODOT" --headless --path project --script bake_asset_index.gd || {
+	echo "asset_index bake failed" >&2; exit 1; }
+
+# 2. zip -0 (store): DDS/gr2 barely compress and we want fast random access from
+#    FileAccess; -X drops extra file attrs. Paths stay assets/... bgm/... so they
+#    mount as res://assets/... res://bgm/...
+mkdir -p build/export
+rm -f "$OUT"
+zip -0 -r -X "$OUT" assets bgm \
+	-x '*/.git/*' -x '*.DS_Store' -x 'assets/.gdignore'
+
+SZ=$(du -h "$OUT" | cut -f1)
+N=$(unzip -l "$OUT" | tail -1 | awk '{print $2}')
+echo
+echo ">> $OUT  ($SZ, $N entries)"
+echo ">> Android:  adb push $OUT /sdcard/Android/data/org.internal.mtgodotpoc/files/"