feat: add dedicated YouTube transcript API endpoint

## CHANGES

- Add new YouTube handler for transcript requests
- Create `/youtube/transcript` POST endpoint route
- Add request/response types for YouTube API
- Support language and timestamp options
- Update frontend to use new endpoint
- Remove chat endpoint dependency for transcripts
- Validate video vs playlist URLs properly

restapi/serve.go

@@ -26,6 +26,7 @@ func Serve(registry *core.PluginRegistry, address string, apiKey string) (err er
 	NewContextsHandler(r, fabricDb.Contexts)
 	NewSessionsHandler(r, fabricDb.Sessions)
 	NewChatHandler(r, registry, fabricDb)
+	NewYouTubeHandler(r, registry)
 	NewConfigHandler(r, fabricDb)
 	NewModelsHandler(r, registry.VendorManager)
 	NewStrategiesHandler(r)

restapi/youtube.go

@@ -0,0 +1,70 @@
+package restapi
+
+import (
+	"net/http"
+
+	"github.com/danielmiessler/fabric/core"
+	"github.com/danielmiessler/fabric/plugins/tools/youtube"
+	"github.com/gin-gonic/gin"
+)
+
+type YouTubeHandler struct {
+	yt *youtube.YouTube
+}
+
+type YouTubeRequest struct {
+	URL        string `json:"url"`
+	Language   string `json:"language"`
+	Timestamps bool   `json:"timestamps"`
+}
+
+type YouTubeResponse struct {
+	Transcript string `json:"transcript"`
+	Title      string `json:"title"`
+}
+
+func NewYouTubeHandler(r *gin.Engine, registry *core.PluginRegistry) *YouTubeHandler {
+	handler := &YouTubeHandler{yt: registry.YouTube}
+	r.POST("/youtube/transcript", handler.Transcript)
+	return handler
+}
+
+func (h *YouTubeHandler) Transcript(c *gin.Context) {
+	var req YouTubeRequest
+	if err := c.BindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid request"})
+		return
+	}
+	if req.URL == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "url is required"})
+		return
+	}
+	language := req.Language
+	if language == "" {
+		language = "en"
+	}
+
+	var videoID, playlistID string
+	var err error
+	if videoID, playlistID, err = h.yt.GetVideoOrPlaylistId(req.URL); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+	if videoID == "" && playlistID != "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "URL is a playlist, not a video"})
+		return
+	}
+
+	var transcript string
+	if req.Timestamps {
+		transcript, err = h.yt.GrabTranscriptWithTimestamps(videoID, language)
+	} else {
+		transcript, err = h.yt.GrabTranscript(videoID, language)
+	}
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, YouTubeResponse{Transcript: transcript, Title: videoID})
+}