fix: add cmd/streamdeck-lets-go, anchor .gitignore to root

The .gitignore pattern 'streamdeck-lets-go' matched the cmd/ directory
name, silently preventing the entrypoint from being tracked since the
restructure. Anchoring to '/streamdeck-lets-go' fixes this while still
ignoring the build binary at repo root.

.gitignore

@@ -1,4 +1,4 @@
-streamdeck-lets-go
+/streamdeck-lets-go
 *.test
 *.out
 *.exe

cmd/streamdeck-lets-go/main.go

@@ -0,0 +1,137 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"os"
+	"os/signal"
+	"strings"
+	"syscall"
+
+	_ "image/gif"
+	_ "image/jpeg"
+	_ "image/png"
+
+	"streamdeck-lets-go/internal/config"
+	"streamdeck-lets-go/internal/daemon"
+	"streamdeck-lets-go/internal/deck"
+)
+
+func main() {
+	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelInfo})))
+
+	fs := flag.NewFlagSet("streamdeck-lets-go", flag.ExitOnError)
+	configPath := fs.String("config", "", "path to config.json (default: ~/.config/streamdeck-lets-go/config.json)")
+	httpAddr := fs.String("addr", ":9090", "web UI listen address")
+	startPage := fs.String("page", "", "page to activate on startup (default: config's default_page)")
+	noDeck := fs.Bool("no-deck", false, "run without Stream Deck hardware (config editing only)")
+	verbose := fs.Bool("v", false, "verbose output")
+
+	if len(os.Args) < 2 || os.Args[1] == "--help" || os.Args[1] == "-help" || os.Args[1] == "-h" {
+		fmt.Fprintf(os.Stderr, "Usage: streamdeck-lets-go [flags] [command]\n\n")
+		fmt.Fprintf(os.Stderr, "Commands:\n")
+		fmt.Fprintf(os.Stderr, "  daemon   run the Stream Deck daemon with web UI (default)\n")
+		fmt.Fprintf(os.Stderr, "  switch   switch running daemon to a page (e.g. 'switch games')\n")
+		fmt.Fprintf(os.Stderr, "  discover list connected Stream Decks\n")
+		fmt.Fprintf(os.Stderr, "\nFlags:\n")
+		fs.PrintDefaults()
+		os.Exit(0)
+	}
+
+	cmd := os.Args[1]
+	args := os.Args[2:]
+
+	switch cmd {
+	case "daemon":
+		fs.Parse(args)
+	case "switch":
+		fs.Parse(args)
+		if fs.NArg() == 0 {
+			fmt.Fprintf(os.Stderr, "Usage: streamdeck-lets-go switch <page>\n")
+			os.Exit(1)
+		}
+		if err := switchToPage(*httpAddr, fs.Arg(0)); err != nil {
+			fmt.Fprintf(os.Stderr, "error: %v\n", err)
+			os.Exit(1)
+		}
+		fmt.Printf("switched to page %q\n", fs.Arg(0))
+		return
+	case "discover":
+		discover()
+		return
+	default:
+		if cmd == "serve" {
+			fmt.Fprintf(os.Stderr, "streamdeck-lets-go: 'serve' removed; use 'daemon --no-deck' instead\n")
+			os.Exit(1)
+		}
+		fs.Parse(os.Args[1:])
+	}
+
+	if *verbose {
+		slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelDebug})))
+	}
+
+	cfg, err := config.LoadConfig(*configPath)
+	if err != nil {
+		slog.Error("config", "error", err)
+		os.Exit(1)
+	}
+
+	ctx, cancel := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	defer cancel()
+
+	httpEnabled := true
+	if err := daemon.Run(ctx, cfg, daemon.RunOptions{
+		ConfigPath:  *configPath,
+		HTTPAddr:    *httpAddr,
+		HTTPEnabled: httpEnabled,
+		NoDeck:      *noDeck,
+		StartPage:   *startPage,
+	}); err != nil {
+		slog.Error("run", "error", err)
+		os.Exit(1)
+	}
+}
+
+func discover() {
+	devices, err := deck.EnumerateDevices()
+	if err != nil {
+		slog.Error("discover", "error", err)
+		os.Exit(1)
+	}
+	if len(devices) == 0 {
+		fmt.Println("No Stream Deck devices found.")
+		return
+	}
+	fmt.Printf("Found %d Stream Deck(s):\n", len(devices))
+	for _, d := range devices {
+		fmt.Printf("  Serial: %s  Model: %s  PID: 0x%04x\n", d.Serial, d.Model, d.PID)
+	}
+}
+
+// switchToPage tells the running daemon (at httpAddr) to activate the given page
+// by POSTing to its /api/activate-page endpoint.
+func switchToPage(httpAddr, page string) error {
+	host := httpAddr
+	if strings.HasPrefix(host, ":") {
+		host = "127.0.0.1" + host
+	}
+	url := "http://" + host + "/api/activate-page"
+
+	body, _ := json.Marshal(map[string]string{"page": page})
+	resp, err := http.Post(url, "application/json", bytes.NewReader(body))
+	if err != nil {
+		return fmt.Errorf("daemon not running? %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("switch failed (HTTP %d)", resp.StatusCode)
+	}
+	return nil
+}