test(bench): cross-library benchmarks vs top 5 go telegram libraries

Adds test/benchmarks/ as a separate Go module so competitor deps
(go-telegram-bot-api/v5, telebot.v3, go-telegram/bot, telego,
echotron/v3) stay out of the root go.mod.

Hot paths covered:
  - Webhook decode  (small Update -> typed Update struct)
  - Large unmarshal (Update with entities + reply markup + photo array)
  - API round-trip  (sendMessage against httptest.Server)
  - Dispatch route  (20 handlers, last-registered matches)

Results on Apple M4 Max / go1.26.2: ours wins 3 of 4 paths and is
2nd of 5 in the round-trip path. Full report at
docs/benchmarks/2026-05-10-comparison.md, raw output committed under
test/benchmarks/results/.

Caveats called out in the report:
  - codec asymmetry (we ship goccy/go-json; competitors mostly stdlib)
  - echotron call bench skipped — built-in rate limiter not externally
    configurable; would measure throttling, not the library
  - dispatch bench limited to libs with a public sync entry point
    (ours, telebot, gobot); gotba has no dispatcher, telego/echotron
    use channel/per-chat paradigms not directly comparable

Also gitignores docs/superpowers/ (local brainstorm/spec scratch)
and regenerates docs/reference/dispatch.md after the new
Router.Process method.

test/benchmarks/README.md

@@ -0,0 +1,36 @@
+# Cross-library benchmarks
+
+Apples-to-apples micro-benchmarks comparing `lukaszraczylo/go-telegram` against the five most-starred Go Telegram libraries:
+
+- `github.com/go-telegram-bot-api/telegram-bot-api/v5`
+- `gopkg.in/telebot.v3` (tucnak)
+- `github.com/go-telegram/bot`
+- `github.com/mymmrac/telego`
+- `github.com/NicoNex/echotron/v3`
+
+Lives in its own Go module so competitor dependencies don't leak into the main repo's `go.mod`.
+
+## Run
+
+```bash
+go test -count=10 -bench=. -benchmem | tee results/raw.txt
+go install golang.org/x/perf/cmd/benchstat@latest    # one-time
+benchstat results/raw.txt > results/benchstat.txt
+```
+
+## Hot paths covered
+
+| File | Path |
+|------|------|
+| `webhook_bench_test.go` | Decode small text-message Update from JSON |
+| `unmarshal_bench_test.go` | Decode large Update (entities + reply markup + photo array) |
+| `call_bench_test.go` | `sendMessage` round-trip against `httptest.Server` |
+| `dispatch_bench_test.go` | Route an Update through 20 registered handlers (worst-case match) |
+
+## Fixtures
+
+`shared/fixtures.go` defines the JSON payloads and the mock HTTP server. Every library decodes the same bytes; every round-trip hits the same canned response.
+
+## Latest results
+
+See [`../../docs/benchmarks/2026-05-10-comparison.md`](../../docs/benchmarks/2026-05-10-comparison.md) for the rendered comparison.