feat(video): add video upload with remux/transcode playback

Add video as a media kind in photos: streaming upload with per-kind
limits, ffprobe metadata, poster frame reusing the image variant
pipeline, and a playback object (remux when web-compatible, else
h264/yuv420p/aac transcode). Video jobs run on a separate pool with a
long lease. Frontend gains a video viewer, grid badge/duration and
video upload.

backend/internal/app/app.go

@@ -24,6 +24,7 @@ import (
 	"galo/internal/sse"
 	"galo/internal/storage"
 	"galo/internal/store"
+	"galo/internal/video"
 )
 
 type Server struct {
@@ -42,6 +43,8 @@ type Server struct {
 	photos *photos.Service
 	worker *photos.Worker
 
+	videoTools *video.Toolchain
+
 	social *social.Service
 
 	notifications *notifications.Service
@@ -62,6 +65,12 @@ func New(cfg *config.Config, repos store.Repos, ping func(ctx context.Context) e
 	photosSvc := photos.NewService(repos.Photos, albumsSvc, st, hub)
 	photosWorker := photos.NewWorker(photosSvc, cfg.Worker.Interval, cfg.Worker.Batch, cfg.Worker.PendingTTL, cfg.Worker.Concurrency)
 
+	videoTools := video.Detect(cfg.Video)
+	photosSvc.SetUploadLimits(cfg.Upload.ImageMaxBytes, cfg.Upload.VideoMaxBytes)
+	photosSvc.SetVideoEnabled(videoTools.Available())
+	photosSvc.SetTempDir(cfg.Video.TempDir)
+	photosWorker.SetVideo(videoTools, cfg.Video.TranscodeConcurrency)
+
 	socialSvc := social.NewService(repos.Social, albumsSvc, repos.Photos, hub, notifSvc)
 
 	shareSvc := sharelinks.NewService(repos.ShareLinks, albumsSvc)
@@ -77,6 +86,7 @@ func New(cfg *config.Config, repos store.Repos, ping func(ctx context.Context) e
 		membersSvc:    membersSvc,
 		photos:        photosSvc,
 		worker:        photosWorker,
+		videoTools:    videoTools,
 		social:        socialSvc,
 		notifications: notifSvc,
 		share:         shareSvc,
@@ -188,13 +198,19 @@ func (s *Server) health(c *gin.Context) {
 	if err := s.storage.Ping(ctx); err != nil {
 		storeStatus = "error"
 	}
+	// Video tooling is optional: its absence does not degrade the service, but
+	// it is reported so operators can see why video upload is disabled.
+	videoStatus := "ok"
+	if !s.videoTools.Available() {
+		videoStatus = "unavailable"
+	}
 	status := http.StatusOK
 	overall := "ok"
 	if dbStatus != "ok" || storeStatus != "ok" {
 		status = http.StatusServiceUnavailable
 		overall = "degraded"
 	}
-	c.JSON(status, gin.H{"status": overall, "db": dbStatus, storageLabel: storeStatus})
+	c.JSON(status, gin.H{"status": overall, "db": dbStatus, storageLabel: storeStatus, "video": videoStatus})
 }
 
 func (s *Server) serveObject(c *gin.Context) {