Live dialogue preview in the editors (reuses the real DialoguePlayer)

- DialoguePlayer gains an `inline` mode (fills its container, no window key
  capture) and a `startId` to jump the walk to a given utterance.
- New DialoguePreview: a scaled-down mini player that fetches the resolved tree
  from GET /api/admin/story-nodes/:id/dialogue (same resolver as playback).
- Mystery graph: preview appears next to a selected dialogue node.
- Utterance editor: docked preview that jumps to the clicked/selected utterance
  and refreshes after each edit.

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

server/index.ts

@@ -289,6 +289,10 @@ app.post('/api/admin/mysteries/:id/graph', requireAdmin, async (req, res, next)
 app.get('/api/admin/story-nodes/:id/utterances', requireAdmin, async (req, res, next) => {
   try { res.json(await storyGraph.listUtterances(String(req.params.id))) } catch (error) { next(error) }
 })
+// Resolved runtime dialogue tree for the editor's live preview (same resolver as play).
+app.get('/api/admin/story-nodes/:id/dialogue', requireAdmin, async (req, res, next) => {
+  try { res.json(await narrative.resolveDialogue(String(req.params.id))) } catch (error) { next(error) }
+})
 app.post('/api/admin/story-nodes/:id/utterances', requireAdmin, async (req, res, next) => {
   try {
     if (!requireEditing(res)) return