feat(api): add endpoint to fetch guest list

* implement ListGuests method in store
* create handleGuestList function in API
* add GuestListEntry and GuestList interfaces in UI
* create guest list page to display RSVPs

server/internal/store/store.go

@@ -78,6 +78,30 @@ type RSVP struct {
 	Message string
 }
 
+// ListGuests returns every RSVP'd guest, ordered by submission then entry order.
+func (s *Store) ListGuests() ([]Guest, error) {
+	rows, err := s.db.Query(
+		`SELECT g.name, g.is_child
+		 FROM rsvp_guests g
+		 JOIN rsvps r ON r.id = g.rsvp_id
+		 ORDER BY r.created_at ASC, g.id ASC`,
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var guests []Guest
+	for rows.Next() {
+		var g Guest
+		if err := rows.Scan(&g.Name, &g.IsChild); err != nil {
+			return nil, err
+		}
+		guests = append(guests, g)
+	}
+	return guests, rows.Err()
+}
+
 func (s *Store) InsertRSVP(r RSVP) error {
 	tx, err := s.db.Begin()
 	if err != nil {