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.

client/call_bench_test.go

@@ -0,0 +1,94 @@
+package client
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"net/http"
+	"testing"
+)
+
+// stubDoer returns the same canned response body for every request. It
+// is intentionally minimal — testify mock has its own overhead that
+// would dominate the per-call cost we want to measure.
+type stubDoer struct{ body []byte }
+
+func (s *stubDoer) Do(_ *http.Request) (*http.Response, error) {
+	return &http.Response{
+		StatusCode: http.StatusOK,
+		Body:       io.NopCloser(bytes.NewReader(s.body)),
+		Header:     http.Header{},
+	}, nil
+}
+
+type benchSendReq struct {
+	ChatID int64  `json:"chat_id"`
+	Text   string `json:"text"`
+}
+
+type benchMsgResp struct {
+	MessageID int64  `json:"message_id"`
+	Date      int64  `json:"date"`
+	Text      string `json:"text"`
+}
+
+func BenchmarkCall_BoolResponse(b *testing.B) {
+	d := &stubDoer{body: []byte(`{"ok":true,"result":true}`)}
+	bot := New("123:abc", WithHTTPClient(d))
+	ctx := context.Background()
+	req := &benchSendReq{ChatID: 42, Text: "hi"}
+	b.ReportAllocs()
+	for b.Loop() {
+		if _, err := Call[*benchSendReq, bool](ctx, bot, "setMyCommands", req); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func BenchmarkCall_StructResponse(b *testing.B) {
+	d := &stubDoer{body: []byte(`{"ok":true,"result":{"message_id":1,"date":0,"text":"ok"}}`)}
+	bot := New("123:abc", WithHTTPClient(d))
+	ctx := context.Background()
+	req := &benchSendReq{ChatID: 42, Text: "hi"}
+	b.ReportAllocs()
+	for b.Loop() {
+		if _, err := Call[*benchSendReq, benchMsgResp](ctx, bot, "sendMessage", req); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func BenchmarkEncodeJSONBody(b *testing.B) {
+	codec := DefaultCodec{}
+	req := &benchSendReq{ChatID: 42, Text: "hello, world"}
+	b.ReportAllocs()
+	for b.Loop() {
+		r, err := encodeJSONBody(codec, req)
+		if err != nil {
+			b.Fatal(err)
+		}
+		_ = r
+	}
+}
+
+func BenchmarkDecodeResult_Bool(b *testing.B) {
+	codec := DefaultCodec{}
+	raw := []byte(`{"ok":true,"result":true}`)
+	b.ReportAllocs()
+	for b.Loop() {
+		if _, err := decodeResult[bool](codec, raw); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func BenchmarkDecodeResult_Struct(b *testing.B) {
+	codec := DefaultCodec{}
+	raw := []byte(`{"ok":true,"result":{"message_id":1,"date":0,"text":"ok"}}`)
+	b.ReportAllocs()
+	for b.Loop() {
+		if _, err := decodeResult[benchMsgResp](codec, raw); err != nil {
+			b.Fatal(err)
+		}
+	}
+}