Fix README clarity issues from code review

- Add explicit mkdir -p public before wasm_exec.js copy
- Specify to save app code as main.go
- Specify to save server code as server.go

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

@@ -9,10 +9,18 @@ Get from zero to a running app in under 5 minutes.
 ### Prerequisites
 
 - Go 1.23 or later
-- Copy the WASM support file: `cp "$(go env GOROOT)/misc/wasm/wasm_exec.js" ./public/`
+
+### Project setup
+
+```bash
+mkdir -p public
+cp "$(go env GOROOT)/misc/wasm/wasm_exec.js" ./public/
+```
 
 ### Create your app
 
+Save this as `main.go`:
+
 ```go
 //go:build js && wasm
 
@@ -73,7 +81,7 @@ GOOS=js GOARCH=wasm go build -o public/app.wasm ./main.go
 
 ### Run
 
-Create a simple server or use the built-in host:
+Save this as `server.go`:
 
 ```go
 package main
@@ -90,7 +98,7 @@ func main() {
 }
 ```
 
-Run it:
+Then run:
 
 ```bash
 go run server.go