Add system tray icon, file logging, and fix Windows hotkey conflict

- Adds fyne.io/systray with a programmatic monkey face icon and Quit menu item
- Logs to discord-lobby-mute.log next to the exe so startup errors are visible
  without a console window
- Windows now uses raw Win32 RegisterHotKey in a locked goroutine instead of
  golang.design/x/hotkey, avoiding a deadlock where systray and the hotkey
  library both try to own the main thread message loop
- Build with: GOOS=windows GOARCH=amd64 go build -ldflags "-H windowsgui" -o discord-lobby-mute.exe .

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

main.go

@@ -3,14 +3,15 @@ package main
 import (
 	"encoding/json"
 	"fmt"
+	"io"
 	"log"
 	"os"
 	"path/filepath"
 	"strings"
 
+	"fyne.io/systray"
 	"github.com/bwmarrin/discordgo"
 	"golang.design/x/hotkey"
-	"golang.design/x/mainthread"
 )
 
 type Config struct {
@@ -107,21 +108,27 @@ func toggleMute(dg *discordgo.Session, cfg *Config, muted bool) {
 	for _, vs := range guild.VoiceStates {
 		if vs.ChannelID == cfg.ChannelID && !exempt[vs.UserID] {
 			if err := dg.GuildMemberMute(cfg.GuildID, vs.UserID, muted); err != nil {
-				log.Printf("  warning: user %s: %v", vs.UserID, err)
+				log.Printf("warning: user %s: %v", vs.UserID, err)
 			}
 			count++
 		}
 	}
 	if count == 0 {
-		fmt.Println("  (no users found in channel)")
+		log.Println("(no users found in channel)")
 	} else {
-		fmt.Printf("  %d user(s) affected\n", count)
+		log.Printf("%d user(s) affected", count)
 	}
 }
 
-func main() { mainthread.Init(run) }
-
 func run() {
+	// Log to file next to the executable so errors are visible even without a console.
+	if exe, err := os.Executable(); err == nil {
+		logPath := filepath.Join(filepath.Dir(exe), "discord-lobby-mute.log")
+		if f, err := os.OpenFile(logPath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644); err == nil {
+			log.SetOutput(io.MultiWriter(os.Stderr, f))
+		}
+	}
+
 	cfg, err := loadConfig()
 	if err != nil {
 		log.Fatal(err)
@@ -144,29 +151,38 @@ func run() {
 	defer dg.Close()
 
 	<-ready
-	fmt.Println("Connected to Discord.")
+	log.Println("Connected to Discord.")
 
-	mods, key, err := parseKeybind(cfg.Keybind)
+	keydownCh, err := startHotkey(cfg.Keybind)
 	if err != nil {
-		log.Fatalf("keybind: %v", err)
-	}
-
-	hk := hotkey.New(mods, key)
-	if err := hk.Register(); err != nil {
 		log.Fatalf("register hotkey %q: %v", cfg.Keybind, err)
 	}
-	defer hk.Unregister()
 
-	fmt.Printf("Listening on %s — toggles server mute for channel %s\n", cfg.Keybind, cfg.ChannelID)
+	log.Printf("Listening on %s — toggles server mute for channel %s", cfg.Keybind, cfg.ChannelID)
 
-	muted := false
-	for range hk.Keydown() {
-		muted = !muted
-		if muted {
-			fmt.Print("Muting all users... ")
-		} else {
-			fmt.Print("Unmuting all users... ")
+	go func() {
+		muted := false
+		for range keydownCh {
+			muted = !muted
+			if muted {
+				log.Print("Muting all users...")
+			} else {
+				log.Print("Unmuting all users...")
+			}
+			toggleMute(dg, cfg, muted)
 		}
-		toggleMute(dg, cfg, muted)
-	}
+	}()
+
+	systray.Run(
+		func() {
+			systray.SetIcon(monkeyIcon())
+			systray.SetTooltip("Discord Lobby Mute — " + cfg.Keybind)
+			mQuit := systray.AddMenuItem("Quit", "Quit Discord Lobby Mute")
+			go func() {
+				<-mQuit.ClickedCh
+				systray.Quit()
+			}()
+		},
+		func() {},
+	)
 }