feat: show when there is an active huddle

This introduces a webhook which listens to events from livekit and
updates our firestore stream particle. It keeps the client simple,
reacting to changes to firestore docs.

go/cmd/orion/main.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"os"
 
+	"cloud.google.com/go/firestore"
 	"cloud.google.com/go/storage"
 	pbaero "github.com/flowy-live/llink/genproto/aero"
 	"github.com/flowy-live/llink/internal"
@@ -80,8 +81,17 @@ func main() {
 	waitlistSvc := waitlist.NewService(db.Pool(), aeroSvc)
 	livekitClient := livekit.NewClient()
 
+	// Initialize Firestore client (for webhook-driven updates)
+	gcpProject := utils.MustGetEnv("GCP_PROJECT")
+	firestoreClient, err := firestore.NewClient(ctx, gcpProject)
+	if err != nil {
+		slog.Error("failed to create Firestore client", "error", err)
+		os.Exit(1)
+	}
+	defer firestoreClient.Close()
+
 	// Initialize handler
-	h := handler.NewHandler(authSvc, humanSvc, networkSvc, particleSvc, depotSvc, waitlistSvc, livekitClient)
+	h := handler.NewHandler(authSvc, humanSvc, networkSvc, particleSvc, depotSvc, waitlistSvc, livekitClient, firestoreClient)
 
 	// Helper to wrap handlers with auth middleware
 	withAuth := func(hf http.HandlerFunc) http.Handler {
@@ -102,6 +112,7 @@ func main() {
 	mux.HandleFunc("POST /auth/request-code", h.RequestSignInCode)
 	mux.HandleFunc("POST /auth/sign-in", h.SignIn)
 	mux.HandleFunc("POST /waitlist", h.AddToWaitlist)
+	mux.HandleFunc("POST /livekit/webhook", h.HandleLivekitWebhook)
 
 	// ==========================================================================
 	// Protected routes (auth required)