feat(mediaserver): Plex/Jellyfin/Emby auto-refresh + .strm instant mode

Sprint 1 — Auto-refresh after download:
- New [[mediaserver]] TOML section with kind/url/token/sections
- mediaserver.Refresh() fans out to Plex (partial via section ID auto-mapping
  from file path prefix) and Jellyfin/Emby (full library scan)
- Manager.OnFinalized callback wired in daemon to trigger refresh after
  organize() completes — keeps engine package free of mediaserver dep
- New unarr mediaserver {setup,list,remove,test} commands
- unarr init wizard offers to configure refresh when a server is detected

Sprint 2 — .strm instant mode (cloud + agent):
- Mode strm-to-library handled in daemon dispatch: writes a one-line .strm
  file pointing to the cloud-resolved debrid HTTPS URL, then triggers refresh
- engine.WriteStrm + StrmDestForTask mirror organize()'s naming so Plex/Jellyfin
  see the expected folder structure (Movies/Title (Year)/, TV Shows/Show/Season XX/)
- Atomic write (temp + rename) so partial files never get indexed
- Reports completed/failed status to the cloud via existing agent client

internal/cmd/daemon.go

@@ -17,6 +17,7 @@ import (
 	"github.com/torrentclaw/unarr/internal/config"
 	"github.com/torrentclaw/unarr/internal/engine"
 	"github.com/torrentclaw/unarr/internal/library"
+	"github.com/torrentclaw/unarr/internal/mediaserver"
 	"github.com/torrentclaw/unarr/internal/usenet/download"
 )
 
@@ -237,10 +238,28 @@ func runDaemonStart() error {
 	// Trigger immediate sync when a download slot frees up
 	manager.OnTaskDone = func() { d.TriggerSync() }
 
+	// Trigger Plex/Jellyfin/Emby library refresh after a task finalises so
+	// the new file appears in the user's library within seconds (instead
+	// of waiting for the next periodic scan). No-op if no servers
+	// configured. Errors are logged inside Refresh and never propagate.
+	if len(cfg.MediaServers) > 0 {
+		manager.OnFinalized = func(task *engine.Task) {
+			if task == nil {
+				return
+			}
+			fp := task.SafeFilePath()
+			if fp == "" {
+				return
+			}
+			mediaserver.Refresh(cfg.MediaServers, fp)
+		}
+	}
+
 	// Wire: sync receives new tasks → submit to manager or handle stream
 	d.OnTasksClaimed = func(tasks []agent.Task) {
 		for _, t := range tasks {
-			if t.Mode == "stream" {
+			switch t.Mode {
+			case "stream":
 				if isStreamingTask(t.ID) {
 					continue
 				}
@@ -251,7 +270,9 @@ func runDaemonStart() error {
 				streamRegistry.cancels[t.ID] = streamCancel
 				streamRegistry.mu.Unlock()
 				go handleStreamTask(streamCtx, t, reporter, cfg, agentClient, streamSrv)
-			} else {
+			case "strm-to-library":
+				go handleStrmToLibrary(ctx, t, cfg, agentClient)
+			default:
 				manager.Submit(ctx, t)
 			}
 		}