test(bench): add allocation benchmarks for client/transport/dispatch hot paths

Hermetic benchmarks (no network) covering Call encode+decode, webhook ServeHTTP body parse, and Router dispatch (command/regex/filter). Use Go 1.24+ b.Loop() idiom. .benchstats/baseline.txt pins the pre-optimisation numbers for benchstat comparisons.

transport/webhook_bench_test.go

@@ -0,0 +1,39 @@
+package transport
+
+import (
+	"bytes"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/lukaszraczylo/go-telegram/client"
+)
+
+const benchUpdateBody = `{"update_id":12345,"message":{"message_id":1,"date":1700000000,"chat":{"id":42,"type":"private"},"from":{"id":42,"is_bot":false,"first_name":"User"},"text":"hello world"}}`
+
+func BenchmarkWebhook_ServeHTTP(b *testing.B) {
+	w := NewWebhookServer(client.New("t"), WithBufferSize(1024))
+	body := []byte(benchUpdateBody)
+
+	done := make(chan struct{})
+	go func() {
+		for {
+			select {
+			case <-w.Updates():
+			case <-done:
+				return
+			}
+		}
+	}()
+	defer close(done)
+
+	b.ReportAllocs()
+	for b.Loop() {
+		req := httptest.NewRequest(http.MethodPost, "/", bytes.NewReader(body))
+		rec := httptest.NewRecorder()
+		w.ServeHTTP(rec, req)
+		if rec.Code != http.StatusOK {
+			b.Fatalf("status %d", rec.Code)
+		}
+	}
+}