Session 4: command dispatcher and main entrypoint

Wire Matrix messages to the *arr clients. Dispatcher parses
"<prefix><cmd> <query>", routes movie/tv/music to Radarr/Sonarr/Lidarr,
adds the top hit, and replies in a thread. Unconfigured services reply
with a clear message instead of failing.

main.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"log/slog"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"bellhop/internal/arr"
+	"bellhop/internal/bot"
+	"bellhop/internal/config"
+	"bellhop/internal/matrix"
+)
+
+func main() {
+	configPath := flag.String("config", "config.yaml", "path to config file")
+	flag.Parse()
+
+	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelInfo})))
+
+	cfg, err := config.Load(*configPath)
+	if err != nil {
+		slog.Error("config load failed", "err", err)
+		os.Exit(1)
+	}
+
+	services := bot.Services{}
+	if cfg.Services.Radarr != nil {
+		services.Radarr = arr.NewRadarr(cfg.Services.Radarr)
+	}
+	if cfg.Services.Sonarr != nil {
+		services.Sonarr = arr.NewSonarr(cfg.Services.Sonarr)
+	}
+	if cfg.Services.Lidarr != nil {
+		services.Lidarr = arr.NewLidarr(cfg.Services.Lidarr)
+	}
+
+	mx, err := matrix.New(cfg.Matrix)
+	if err != nil {
+		slog.Error("matrix init failed", "err", err)
+		os.Exit(1)
+	}
+
+	dispatcher := bot.New(cfg.Matrix.CommandPrefix, services, mx)
+	mx.SetMessageHandler(dispatcher.Handle)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	mx.Start(ctx)
+	slog.Info("bellhop started", "allowed_rooms", len(cfg.Matrix.AllowedRooms))
+
+	sig := make(chan os.Signal, 1)
+	signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
+	<-sig
+
+	slog.Info("shutting down")
+	cancel()
+	mx.Stop()
+}