Add standalone Go build alongside VSCode extension

Ports all five tools to a single 7.5 MB Windows exe with an embedded
WebView2 window, file-based config, single-instance focus, and clean
shutdown. Adds build.ps1 to build both targets from one command.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

standalone/main.go

@@ -0,0 +1,171 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+	"os"
+	"path/filepath"
+	"sync/atomic"
+	"syscall"
+	"time"
+	"unsafe"
+
+	webview "github.com/jchv/go-webview2"
+)
+
+var currentHwnd atomic.Uintptr
+
+func setupFileLogging() {
+	logPath := filepath.Join(appDir(), "debug.log")
+	f, err := os.OpenFile(logPath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
+	if err != nil {
+		return
+	}
+	log.SetOutput(f)
+	log.SetFlags(log.LstdFlags | log.Lshortfile)
+}
+
+func main() {
+	setupFileLogging()
+	log.Printf("HPL Toolbox starting (pid=%d)", os.Getpid())
+
+	if focusExistingInstance() {
+		log.Printf("Another instance is running; focused it and exiting.")
+		return
+	}
+
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		log.Fatal(err)
+	}
+	port := listener.Addr().(*net.TCPAddr).Port
+	log.Printf("Server listening on 127.0.0.1:%d", port)
+
+	mux := buildMux()
+	srv := &http.Server{Handler: mux}
+	go func() {
+		if err := srv.Serve(listener); err != nil && err != http.ErrServerClosed {
+			log.Printf("Server error: %v", err)
+		}
+	}()
+
+	if err := writeLockFile(port); err != nil {
+		log.Printf("Failed to write lock file: %v", err)
+	}
+	defer removeLockFile()
+
+	w := webview.NewWithOptions(webview.WebViewOptions{
+		Debug:     false,
+		AutoFocus: true,
+		WindowOptions: webview.WindowOptions{
+			Title:  "HPL Toolbox",
+			Width:  1100,
+			Height: 720,
+			IconId: 1,
+			Center: true,
+		},
+	})
+	if w == nil {
+		log.Fatalln("Failed to create webview.")
+	}
+	defer w.Destroy()
+
+	// Stash HWND for the /api/focus handler.
+	currentHwnd.Store(uintptr(w.Window()))
+
+	w.SetSize(1100, 720, webview.HintNone)
+	w.Navigate(fmt.Sprintf("http://127.0.0.1:%d/", port))
+	w.Run()
+
+	// Window closed — shut the server down cleanly.
+	log.Printf("Window closed; shutting down server.")
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+	_ = srv.Shutdown(ctx)
+}
+
+func buildMux() *http.ServeMux {
+	mux := http.NewServeMux()
+
+	// Pages
+	mux.HandleFunc("GET /", func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/" && r.URL.Path != "/home" {
+			http.NotFound(w, r)
+			return
+		}
+		HomePage(w, r)
+	})
+	mux.HandleFunc("GET /plec", PlecPage)
+	mux.HandleFunc("GET /applovin", ApplovinPage)
+	mux.HandleFunc("GET /base64", Base64Page)
+	mux.HandleFunc("GET /daily", DailyPage)
+	mux.HandleFunc("GET /mobile", MobilePage)
+	mux.HandleFunc("GET /assets/qrcode.min.js", MobileQrScript)
+
+	// Shared API
+	mux.HandleFunc("POST /api/clipboard", ClipboardEndpoint)
+	mux.HandleFunc("POST /api/open", OpenEndpoint)
+	mux.HandleFunc("POST /api/focus", FocusEndpoint)
+
+	// Daily Update
+	mux.HandleFunc("POST /api/daily/submit", DailySubmit)
+
+	// PLEC
+	mux.HandleFunc("POST /api/plec/pick", PlecPick)
+	mux.HandleFunc("POST /api/plec/upload", PlecUpload)
+
+	// AppLovin
+	mux.HandleFunc("POST /api/applovin/pick", ApplovinPick)
+	mux.HandleFunc("POST /api/applovin/upload", ApplovinUpload)
+
+	// Base64
+	mux.HandleFunc("POST /api/base64/pickFolder", Base64PickFolder)
+	mux.HandleFunc("POST /api/base64/pickFiles", Base64PickFiles)
+	mux.HandleFunc("POST /api/base64/scan", Base64Scan)
+
+	// Send To Mobile
+	mux.HandleFunc("POST /api/mobile/pick", MobilePick)
+	mux.HandleFunc("POST /api/mobile/start", MobileStart)
+	mux.HandleFunc("POST /api/mobile/stop", MobileStop)
+
+	return mux
+}
+
+// FocusEndpoint brings the webview window to the foreground. Used by a second
+// instance that wants to focus the running one before exiting.
+func FocusEndpoint(w http.ResponseWriter, r *http.Request) {
+	hwnd := currentHwnd.Load()
+	if hwnd != 0 {
+		restoreAndFocus(hwnd)
+	}
+	w.WriteHeader(http.StatusOK)
+}
+
+var (
+	user32              = syscall.NewLazyDLL("user32.dll")
+	procShowWindow      = user32.NewProc("ShowWindow")
+	procSetForeground   = user32.NewProc("SetForegroundWindow")
+	procIsIconic        = user32.NewProc("IsIconic")
+)
+
+const (
+	swRestore = 9
+	swShow    = 5
+)
+
+func restoreAndFocus(hwnd uintptr) {
+	// If minimized, restore. Otherwise just ensure it's shown.
+	iconic, _, _ := procIsIconic.Call(hwnd)
+	if iconic != 0 {
+		_, _, _ = procShowWindow.Call(hwnd, swRestore)
+	} else {
+		_, _, _ = procShowWindow.Call(hwnd, swShow)
+	}
+	_, _, _ = procSetForeground.Call(hwnd)
+}
+
+// Silence "imported and not used" complaints if any.
+var _ = unsafe.Sizeof(int(0))