Welt-Texturen aus der .glb statt aus assets/textures/

Der Loader zieht jetzt die baseColorTexture jedes Materials aus dem
BIN-Chunk und dekodiert sie (PNG, via png-Crate) → model::Texture mit
Pixeln. Die Namenskonvention "Materialname = Dateiname" und der
assets/textures/-Pfad für Welt-Texturen entfallen; assets/textures/
bleibt nur noch für UI/Fonts/Platzhalter.

- engine::image: neuer, geteilter RGBA8-Image-Typ (aus tga.rs gezogen)
  plus PNG-Decoder. tga.rs liefert weiter denselben Typ.
- gltf: material -> texture -> image -> bufferView auflösen, Bild aus
  BIN dekodieren; fehlt ein Glied, bleibt image None (Platzhalter).
  KHR_texture_transform (Blenders Mapping-Node) wird beim Laden in die
  UVs eingebacken.
- model::Model: materials: Vec<String> -> textures: Vec<Texture>.
- render: die Pixel je Schlüssel aus den Modellen sammeln (erstes
  Vorkommen gewinnt, Schlüssel ohne Bild -> Platzhalter).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0196AM4UyAJEXVtPvp5DdKr8

Cargo.lock

@@ -18,6 +18,12 @@ version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "366ffbaa4442f4684d91e2cd7c5ea7c4ed8add41959a31447066e279e432b618"
 
+[[package]]
+name = "adler2"
+version = "2.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "320119579fcad9c21884f5c4861d16174d0e06250625266f50fe6898340abefa"
+
 [[package]]
 name = "ahash"
 version = "0.8.12"
@@ -410,6 +416,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "crc32fast"
+version = "1.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8498c871161e1742aaa9d52551b2d6ebdd4c3d45a3be423e3728f33b955be550"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "crossbeam-utils"
 version = "0.8.21"
@@ -496,12 +511,32 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "fdeflate"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e6853b52649d4ac5c0bd02320cddc5ba956bdb407c4b75a2c6b75bf51500f8c"
+dependencies = [
+ "simd-adler32",
+]
+
 [[package]]
 name = "find-msvc-tools"
 version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5baebc0774151f905a1a2cc41989300b1e6fbb29aff0ceffa1064fdd3088d582"
 
+[[package]]
+name = "flate2"
+version = "1.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e634e2e0ebac1ee034020da1ca582e17ffe4e0f5e985823721e168928136dcb"
+dependencies = [
+ "crc32fast",
+ "miniz_oxide 0.9.1",
+ "zlib-rs",
+]
+
 [[package]]
 name = "foldhash"
 version = "0.1.5"
@@ -967,6 +1002,26 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
 
+[[package]]
+name = "miniz_oxide"
+version = "0.8.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fa76a2c86f704bdb222d66965fb3d63269ce38518b83cb0575fca855ebb6316"
+dependencies = [
+ "adler2",
+ "simd-adler32",
+]
+
+[[package]]
+name = "miniz_oxide"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b63fbc4a50860e98e7b2aa7804ded1db5cbc3aff9193adaff57a6931bf7c4b4c"
+dependencies = [
+ "adler2",
+ "simd-adler32",
+]
+
 [[package]]
 name = "naga"
 version = "29.0.3"
@@ -1436,6 +1491,19 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b4596b6d070b27117e987119b4dac604f3c58cfb0b191112e24771b2faeac1a6"
 
+[[package]]
+name = "png"
+version = "0.18.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60769b8b31b2a9f263dae2776c37b1b28ae246943cf719eb6946a1db05128a61"
+dependencies = [
+ "bitflags 2.13.0",
+ "crc32fast",
+ "fdeflate",
+ "flate2",
+ "miniz_oxide 0.8.9",
+]
+
 [[package]]
 name = "polling"
 version = "3.11.0"
@@ -1792,6 +1860,12 @@ version = "2.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f8fadd59c855ef2080decdef8ff161eb6661b86933c9d82e5ba29dc602a55aba"
 
+[[package]]
+name = "simd-adler32"
+version = "0.3.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3a219298ac11a56ea9a6d2120044824d6f01aeb034955e7af7bc16858527deea"
+
 [[package]]
 name = "simd_cesu8"
 version = "1.1.1"
@@ -2321,6 +2395,7 @@ version = "0.1.0"
 dependencies = [
  "bladeink",
  "bytemuck",
+ "png",
  "pollster",
  "serde_json",
  "tinyaudio",
@@ -2986,6 +3061,12 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "zlib-rs"
+version = "0.6.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34b31d188d9d685a4f9c7b46d6e36631b07058d2cfe190267adce54dc230bf12"
+
 [[package]]
 name = "zmij"
 version = "1.0.21"