Fix WebGL2 for web build (raylib 5 requires VAOs)

Add -sUSE_WEBGL2=1 -sMIN_WEBGL_VERSION=2 -sMAX_WEBGL_VERSION=2 to both
EMCC_CFLAGS and linker flags. raylib 5.x enables VAOs by default which
require WebGL2; without it glVertexAttribPointer fails on the clientside
property of an undefined VAO object.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.cargo/config.toml

@@ -7,5 +7,7 @@ rustflags = [
     "-C", "link-arg=-sWASM=1",
     "-C", "link-arg=-sALLOW_MEMORY_GROWTH=1",
     "-C", "link-arg=-sINITIAL_MEMORY=67108864",
-    "-C", "link-arg=-sFULL_ES3=1",
+    "-C", "link-arg=-sUSE_WEBGL2=1",
+    "-C", "link-arg=-sMIN_WEBGL_VERSION=2",
+    "-C", "link-arg=-sMAX_WEBGL_VERSION=2",
 ]

build_web.sh

@@ -4,7 +4,7 @@
 set -euo pipefail
 
 # Flags required by raylib-sys for WASM compilation.
-export EMCC_CFLAGS="-O3 -sUSE_GLFW=3 -sASSERTIONS=1 -sWASM=1 -sASYNCIFY -sGL_ENABLE_GET_PROC_ADDRESS=1"
+export EMCC_CFLAGS="-O3 -sUSE_GLFW=3 -sASSERTIONS=1 -sWASM=1 -sASYNCIFY -sGL_ENABLE_GET_PROC_ADDRESS=1 -sUSE_WEBGL2=1 -sMIN_WEBGL_VERSION=2 -sMAX_WEBGL_VERSION=2"
 
 echo "Building for wasm32-unknown-emscripten..."
 cargo build --target wasm32-unknown-emscripten --release
@@ -20,5 +20,5 @@ echo "Build complete. Output in web/"
 
 if [[ "${1-}" == "--serve" ]]; then
   echo "Serving at http://localhost:8080"
-  python3 -m http.server 8080 --directory web
+  cd web && python3 -m http.server 8080
 fi