Add DeleteTorrent to torrent client interface for cancel cleanup

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/claude-agent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

internal/torrent/client.go

@@ -45,5 +45,6 @@ type TorrentClient interface {
 	Find(opts FindOptions) ([]TorrentInfo, error)
 	AddTorrent(file TorrentFile, savePath string) error
 	AddMagnet(magnetURI string, savePath string) error
+	DeleteTorrent(hash string) error
 	DefaultSavePath() (string, error)
 }

internal/torrent/qbittorrent_client.go

@@ -313,6 +313,40 @@ func (t *QbittorrentListItem) toTorrentInfo() TorrentInfo {
 	}
 }
 
+func (c *QbittorrentClient) DeleteTorrent(hash string) error {
+	log.Trace().Str("hash", hash).Msg("qbittorrent deleting torrent")
+
+	data := url.Values{}
+	data.Set("hashes", hash)
+	data.Set("deleteFiles", "true")
+
+	req, err := http.NewRequest("POST", c.baseURL+"/api/v2/torrents/delete", strings.NewReader(data.Encode()))
+	if err != nil {
+		log.Error().Err(err).Msg("qbittorrent creating delete request failed")
+		return fmt.Errorf("creating delete request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.AddCookie(&http.Cookie{Name: "SID", Value: c.sid})
+
+	start := time.Now()
+	resp, err := c.client.Do(req)
+	if err != nil {
+		log.Error().Err(err).Msg("qbittorrent delete request failed")
+		return fmt.Errorf("delete request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	log.Trace().Int("status", resp.StatusCode).Dur("duration", time.Since(start)).Msg("qbittorrent delete response")
+
+	if resp.StatusCode != http.StatusOK {
+		log.Error().Int("status", resp.StatusCode).Msg("qbittorrent delete returned non-OK status")
+		return fmt.Errorf("delete torrent returned status %d", resp.StatusCode)
+	}
+
+	log.Info().Str("hash", hash).Msg("qbittorrent torrent deleted")
+	return nil
+}
+
 func (c *QbittorrentClient) DefaultSavePath() (string, error) {
 	req, err := http.NewRequest("GET", c.baseURL+"/api/v2/app/defaultSavePath", nil)
 	if err != nil {