fix CORS headers and a wasm experiment

pkg/wasm/hello/README.md

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+# WebAssembly Test Server
+
+Simple Go web server for serving WebAssembly files with correct MIME types.
+
+## Quick Start
+
+```bash
+# Build and run the server
+go run server.go
+
+# Or with custom port
+go run server.go -port 3000
+
+# Or serve from a different directory
+go run server.go -dir /path/to/wasm/files
+```
+
+## Build and Install
+
+```bash
+# Build binary
+go build -o wasm-server server.go
+
+# Run
+./wasm-server
+
+# Install to PATH
+go install
+```
+
+## Usage
+
+Once the server is running, open your browser to:
+- http://localhost:8080/
+
+The server will serve:
+- `index.html` - Main HTML page
+- `hello.js` - JavaScript loader for WASM
+- `hello.wasm` - WebAssembly binary module
+- `hello.wat` - WebAssembly text format (for reference)
+
+## Files
+
+- **server.go** - Go web server with WASM MIME type support
+- **index.html** - HTML page that loads the WASM module
+- **hello.js** - JavaScript glue code to instantiate and run WASM
+- **hello.wasm** - Compiled WebAssembly binary
+- **hello.wat** - WebAssembly text format source
+
+## Building WASM Files
+
+### From WAT (WebAssembly Text Format)
+
+```bash
+# Install wabt tools
+sudo apt install wabt
+
+# Compile WAT to WASM
+wat2wasm hello.wat -o hello.wasm
+
+# Disassemble WASM back to WAT
+wasm2wat hello.wasm -o hello.wat
+```
+
+### From Go (using TinyGo)
+
+```bash
+# Install TinyGo
+wget https://github.com/tinygo-org/tinygo/releases/download/v0.31.0/tinygo_0.31.0_amd64.deb
+sudo dpkg -i tinygo_0.31.0_amd64.deb
+
+# Create Go program
+cat > main.go << 'EOF'
+package main
+
+import "fmt"
+
+func main() {
+    fmt.Println("Hello from Go WASM!")
+}
+EOF
+
+# Compile to WASM
+tinygo build -o main.wasm -target=wasm main.go
+
+# Get the WASM runtime helper
+cp $(tinygo env TINYGOROOT)/targets/wasm_exec.js .
+```
+
+## Browser Console
+
+Open your browser's developer console (F12) to see the output from the WASM module.
+
+The `hello.wasm` module should print "Hello, World!" to the console.
+
+## CORS Headers
+
+The server includes CORS headers to allow:
+- Cross-origin requests during development
+- Loading WASM modules from different origins
+
+This is useful when developing and testing WASM modules.