fix: correct Telegram update/keyboard models and harden env parsing

handler_test.go

@@ -0,0 +1,14 @@
+package laniakea
+
+import "testing"
+
+func TestCheckPrefixesSkipsEmptyPrefixes(t *testing.T) {
+	bot := &Bot[NoDB]{prefixes: []string{"", "/"}}
+
+	if prefix, ok := bot.checkPrefixes("hello"); ok {
+		t.Fatalf("unexpected prefix match for plain text: %q", prefix)
+	}
+	if prefix, ok := bot.checkPrefixes("/start"); !ok || prefix != "/" {
+		t.Fatalf("unexpected prefix result: prefix=%q ok=%v", prefix, ok)
+	}
+}