feat(send): implement SendChatAction

Map the ChatAction enum onto the gotd typing-action builder (typing, upload/
record photo/video/voice/document, choose sticker, find location, video note).
The switch is exhaustive; unknown actions return a 400.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: ernado

send_action.go

@@ -0,0 +1,44 @@
+package botapi
+
+import "context"
+
+// SendChatAction tells the chat that the bot is performing an action (e.g.
+// "typing"). The status is cleared automatically after a short period or when
+// the next message is sent.
+//
+// The switch over ChatAction is exhaustive (exhaustive lint).
+func (b *Bot) SendChatAction(ctx context.Context, chat ChatID, action ChatAction) error {
+	peer, err := b.resolveInputPeer(ctx, chat)
+	if err != nil {
+		return err
+	}
+
+	a := b.sender.To(peer).TypingAction()
+	switch action {
+	case ChatActionTyping:
+		err = a.Typing(ctx)
+	case ChatActionUploadPhoto:
+		err = a.UploadPhoto(ctx, 0)
+	case ChatActionRecordVideo:
+		err = a.RecordVideo(ctx)
+	case ChatActionUploadVideo:
+		err = a.UploadVideo(ctx, 0)
+	case ChatActionRecordVoice:
+		err = a.RecordAudio(ctx)
+	case ChatActionUploadVoice:
+		err = a.UploadAudio(ctx, 0)
+	case ChatActionUploadDocument:
+		err = a.UploadDocument(ctx, 0)
+	case ChatActionChooseSticker:
+		err = a.ChooseSticker(ctx)
+	case ChatActionFindLocation:
+		err = a.GeoLocation(ctx)
+	case ChatActionRecordVideoNote:
+		err = a.RecordRound(ctx)
+	case ChatActionUploadVideoNote:
+		err = a.UploadRound(ctx, 0)
+	default:
+		return &Error{Code: 400, Description: "Bad Request: wrong parameter action in request"}
+	}
+	return asAPIError(err)
+}