M2.5: ShaderMaterial + texture resolution + fog; multi-skeleton verified

- m2_material: Metin2-style ShaderMaterial. blend_mix shader (opaque /
  alpha-blend / alpha-test-cutout via `mode` uniform) + blend_add shader
  (additive glow). modulate(tex, COORD) * COLOR, diffuse_lambert.
- Metin2Model: material_mode prop ("metin2" ShaderMaterial | "standard");
  _resolve_texture does filename-convention + case-insensitive dir scan of
  *.dds (face/hair keyword slots, stem match, fallback); set_surface_texture
  override; guess_blend heuristic (hair->cutout, cape->alpha, effect->add).
  Texture cache. Fixed opaque path to NOT alpha-discard (was hiding bodies).
- harness: AABB-based camera framing, engine depth fog (MTGODOT_FOG=1),
  MTGODOT_ANIM_T fixed-pose capture (needs explicit anim reload first),
  MTGODOT_AUTOSHOT batch screenshot.

Verified: warrior 5/5 surfaces textured under the shader (t=9 dance pose,
lit, fogged). assassin 17/17 textured via dir scan. shaman_lord (gr2 v7)
renders. Screenshots test/golden/m25-*.png, m2c-t*.png.

Gap (M2.5 gate not closed): libgr2 POD API exposes no material/texture-name/
blend data, so multi-slot -> texture/blend mapping is heuristic only. Needs
a libgr2 material API (gr2_material.cpp walking the type tree) — same gap as
xrender-poc M1 T5. Documented in docs/GODOT-POC-PLAN.md §M2.5 T2.5.6.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WaHYEY9rwLWt21PULiYjeJ

extension/src/metin2_model.h

@@ -1,6 +1,10 @@
 #pragma once
 
+#include <godot_cpp/classes/image_texture.hpp>
 #include <godot_cpp/classes/node3d.hpp>
+#include <godot_cpp/classes/ref.hpp>
+#include <godot_cpp/templates/hash_map.hpp>
+#include <godot_cpp/variant/packed_string_array.hpp>
 #include <godot_cpp/variant/string.hpp>
 
 #include <gr2/gr2.h>
@@ -11,6 +15,7 @@
 namespace godot {
 class Skeleton3D;
 class MeshInstance3D;
+class ImageTexture;
 } // namespace godot
 
 namespace mtgodot {
@@ -46,6 +51,12 @@ public:
 	void set_flip_winding(bool v);
 	bool get_flip_winding() const { return flip_winding; }
 
+	void set_material_mode(const godot::String &m);
+	godot::String get_material_mode() const { return material_mode; }
+
+	// Explicit per-surface texture path override (index -> absolute .dds path).
+	void set_surface_texture(int surface, const godot::String &path);
+
 	// Rebuild the subtree from the current properties.
 	void reload();
 
@@ -69,14 +80,22 @@ private:
 	bool flip_z = false;
 	bool flip_winding = false;
 
+	godot::String material_mode = "metin2"; // "metin2" (ShaderMaterial) | "standard"
+	godot::PackedStringArray surface_tex_override;
+
 	std::shared_ptr<std::optional<gr2::File>> file; // shared_ptr so accessor stays valid
 	godot::Skeleton3D *skel = nullptr;
 	godot::MeshInstance3D *mi = nullptr;
 	godot::String last_info;
+	godot::HashMap<godot::String, godot::Ref<godot::ImageTexture>> tex_cache;
 
 	void _clear_children();
 	void _apply_materials();
 	godot::String _guess_texture_dir() const;
+	godot::Ref<godot::ImageTexture> _load_dds(const godot::String &path);
+	godot::Ref<godot::ImageTexture> _resolve_texture(const godot::String &dir,
+			const godot::String &stem, const godot::String &surface_name,
+			const godot::PackedStringArray &dds_files);
 };
 
 } // namespace mtgodot