Fix calculator example build by removing obsolete files and adding codegen workarounds

Changes:
- Remove obsolete calculator.go and helpers.go (functionality moved to calculator.gx)
- Remove duplicate console/log declarations from main.go (now in generated code)
- Update app.gx to use make(chan CalculatorState, 10) instead of NewCalculatorStateChannel()
- Add automated patching to build.sh to work around codegen issues:
  * Fix stateChannel references in closures (should use c.StateChannel)
  * Initialize state channel with default value in NewApp()
- Update build.sh with proper wasm_exec.js fallback logic

The calculator now builds successfully with all state management handled through channels.

Author: claude

examples/calculator/app.gx

@@ -1,7 +1,7 @@
 package main
 
 func App() (Component) {
-	stateChannel := NewCalculatorStateChannel()
+	stateChannel := make(chan CalculatorState, 10)
 
 	Div(Class("app-container")) {
 		H1 {

examples/calculator/build.sh

@@ -9,9 +9,29 @@ cd ../..
 go run ./cmd/guix generate -p examples/calculator
 cd examples/calculator
 
+# Patch generated files to workaround codegen issues
+echo "Patching generated code..."
+# Fix stateChannel references in calculator_gen.go
+sed -i 's/handleNumber(stateChannel,/handleNumber(c.StateChannel,/g' calculator_gen.go
+sed -i 's/handleOperator(stateChannel,/handleOperator(c.StateChannel,/g' calculator_gen.go
+sed -i 's/handleClear(stateChannel)/handleClear(c.StateChannel)/g' calculator_gen.go
+sed -i 's/handleEquals(stateChannel,/handleEquals(c.StateChannel,/g' calculator_gen.go
+
+# Initialize the state channel with initial value in app_gen.go
+sed -i '/c.stateChannel = make(chan CalculatorState, 10)/a\	c.stateChannel <- CalculatorState{Display: "0", PreviousValue: 0, Operator: "", WaitingForOperand: false}' app_gen.go
+
 # Copy wasm_exec.js
 echo "Copying wasm_exec.js..."
-cp "$(go env GOROOT)/misc/wasm/wasm_exec.js" .
+GOROOT="$(go env GOROOT)"
+# Try lib/wasm first (Go 1.24+), then misc/wasm (older versions)
+if [ -f "$GOROOT/lib/wasm/wasm_exec.js" ]; then
+  cp "$GOROOT/lib/wasm/wasm_exec.js" .
+elif [ -f "$GOROOT/misc/wasm/wasm_exec.js" ]; then
+  cp "$GOROOT/misc/wasm/wasm_exec.js" .
+else
+  echo "wasm_exec.js not found in GOROOT, downloading from GitHub"
+  curl -o wasm_exec.js https://raw.githubusercontent.com/golang/go/go1.25.0/lib/wasm/wasm_exec.js
+fi
 
 # Build WASM
 echo "Building WASM..."

examples/calculator/calculator.go

@@ -4,17 +4,9 @@
 package main
 
 import (
-	"syscall/js"
-
 	"github.com/gaarutyunov/guix/pkg/runtime"
 )
 
-var console = js.Global().Get("console")
-
-func log(args ...interface{}) {
-	console.Call("log", args...)
-}
-
 func main() {
 	log("MAIN: Starting calculator example")