feat: anonymous adoption telemetry on first client.New

Sends one fire-and-forget POST per process the first time a consumer
constructs a Bot via client.New. Helps track real-world adoption and
version spread of the library. No identifiers, no API contents.

Implementation:
- new client/version.go: exported Version var (currently 0.7.11)
- new client/telemetry.go: sync.Once gate + telemetry.Send call
- client.go New(): single fireTelemetryOnce() line at function entry
- client/telemetry_test.go: TestMain disables outgoing pings during the
  library's own test suite

README §Telemetry documents the payload, the opt-out env vars, and links
to the upstream oss-telemetry source so consumers can audit what is sent.

Opt out via any of:
  DO_NOT_TRACK=1
  OSS_TELEMETRY_DISABLED=1
  GO_TELEGRAM_DISABLE_TELEMETRY=1
  osstelemetry.Disable() before the first client.New

go.mod

@@ -4,7 +4,9 @@ go 1.25.0
 
 require (
 	github.com/goccy/go-json v0.10.6
+	github.com/lukaszraczylo/oss-telemetry v0.0.0-20260521005811-e02d51419c52
 	github.com/stretchr/testify v1.9.0
+	github.com/valyala/fasthttp v1.71.0
 	golang.org/x/net v0.54.0
 )
 
@@ -15,6 +17,5 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/stretchr/objx v0.5.2 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
-	github.com/valyala/fasthttp v1.71.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )