Admin: create/delete mysteries, asset library, cutscene component picker

- Mysteries tab: "+ New" (slug + title) and per-row delete; opens the graph editor.
- Assets tab: upload images/audio/PDFs to the shared osint.assets store, grid with
  thumbnails/icons, copy id/url, delete (blocked with 409 when the asset is in use).
- Cutscene component_key is now a datalist of registered keys with a
  "not registered" warning, instead of free text.

Backend: DELETE /api/admin/mysteries/:id and POST/GET/DELETE /api/admin/assets
(reusing the deduplicated, MinIO-backed asset store).

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

src/mysteryGraph.tsx

@@ -1,5 +1,6 @@
 import { useCallback, useEffect, useRef, useState } from 'react'
 import { UtteranceCanvas } from './utteranceCanvas'
+import { CUTSCENE_COMPONENT_KEYS } from './narrative'
 
 type StoryNodeType = 'cutscene' | 'dialogue' | 'level' | 'det_gate' | 'llm_gate'
 type Terminal = { id: string; terminalKey: string; label: string; toNodeId: string | null; sortOrder: number }
@@ -181,7 +182,10 @@ function NodeInspector({ node, graph, templates, onPatch, onSetEntry, onDelete,
         <option value="">— choose —</option>
         {templates.map(t => <option key={t.versionId} value={t.versionId}>{t.name} (v{t.version})</option>)}
       </select></label>}
-    {usesComponent && <label className="ins-field"><span>Component key</span><input value={componentKey} placeholder={node.nodeType === 'cutscene' ? 'glass-harbour-diversion' : 'det_gate_lvl_1'} onChange={e => setComponentKey(e.target.value)} onBlur={() => componentKey !== (node.componentKey || '') && onPatch({ componentKey })} /></label>}
+    {usesComponent && <label className="ins-field"><span>Component key{node.nodeType === 'cutscene' && componentKey && !CUTSCENE_COMPONENT_KEYS.includes(componentKey) && <b className="ins-warn"> · not registered</b>}</span>
+      <input list={node.nodeType === 'cutscene' ? 'cutscene-components' : undefined} value={componentKey} placeholder={node.nodeType === 'cutscene' ? 'glass-harbour-diversion' : 'det_gate_lvl_1'} onChange={e => setComponentKey(e.target.value)} onBlur={() => componentKey !== (node.componentKey || '') && onPatch({ componentKey })} />
+      {node.nodeType === 'cutscene' && <datalist id="cutscene-components">{CUTSCENE_COMPONENT_KEYS.map(k => <option key={k} value={k} />)}</datalist>}
+    </label>}
     {(node.nodeType === 'dialogue' || node.nodeType === 'cutscene') && <label className="ins-check"><input type="checkbox" checked={node.hasUtterances} onChange={e => onPatch({ hasUtterances: e.target.checked })} /> Has utterances</label>}
     {(node.nodeType === 'dialogue' || node.hasUtterances) && <button className="ins-utterances" onClick={onEditUtterances}>Edit utterances →</button>}