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>

server/narrativeRepository.ts

@@ -4,6 +4,7 @@ import { cloneBoard } from './boardClone.js'
 import type { ObjectStorage } from './objectStorage.js'
 
 export type UploadedFile = { buffer: Buffer; originalname: string; mimetype: string; size: number }
+export type AssetDto = { id: string; originalName: string; mimeType: string; byteSize: number; url: string }
 export type PoseDto = { poseKey: string; assetId: string; url: string }
 export type NpcDto = { id: string; key: string; name: string; role: string; defaultPose: string | null; poses: PoseDto[]; inUse: boolean }
 export type MysterySummary = { id: string; slug: string; title: string; nodes: number }
@@ -46,6 +47,10 @@ export interface NarrativeRepository {
   getCurrentPlaythrough(userId: string): Promise<PlaythroughState | null>
   advancePlaythrough(userId: string, playthroughId: string, terminalKey?: string): Promise<{ ok: boolean; state?: PlaythroughState; error?: string }>
   listMysteries(): Promise<MysterySummary[]>
+  deleteMystery(id: string): Promise<boolean>
+  uploadAsset(file: UploadedFile): Promise<AssetDto>
+  listAssets(): Promise<AssetDto[]>
+  deleteAsset(id: string): Promise<'deleted' | 'in_use' | 'not_found'>
   listNpcs(): Promise<NpcDto[]>
   createNpc(input: { key: string; name: string; role?: string; defaultPose?: string | null }): Promise<NpcDto>
   updateNpc(id: string, input: { name?: string; role?: string; defaultPose?: string | null }): Promise<NpcDto | null>
@@ -259,6 +264,36 @@ export function createNarrativeRepository(pool: Pool, objectStorage: ObjectStora
       return result.rows.map(row => ({ id: row.id, slug: row.slug, title: row.title, nodes: Number(row.nodes) }))
     },
 
+    async deleteMystery(id) {
+      const result = await pool.query('DELETE FROM osint.mysteries WHERE id=$1', [id])
+      return (result.rowCount ?? 0) > 0
+    },
+
+    async uploadAsset(file) {
+      const id = await storeAsset(file)
+      const row = (await pool.query<{ original_name: string; mime_type: string; byte_size: string }>(
+        'SELECT original_name,mime_type,byte_size FROM osint.assets WHERE id=$1', [id])).rows[0]
+      return { id, originalName: row.original_name, mimeType: row.mime_type, byteSize: Number(row.byte_size), url: `/api/assets/${id}` }
+    },
+
+    async listAssets() {
+      const result = await pool.query<{ id: string; original_name: string; mime_type: string; byte_size: string }>(
+        'SELECT id,original_name,mime_type,byte_size FROM osint.assets ORDER BY created_at DESC')
+      return result.rows.map(row => ({ id: row.id, originalName: row.original_name, mimeType: row.mime_type, byteSize: Number(row.byte_size), url: `/api/assets/${row.id}` }))
+    },
+
+    async deleteAsset(id) {
+      // document_exhibits.asset_id is ON DELETE RESTRICT, so an in-use asset raises a
+      // foreign-key violation (23503) rather than deleting.
+      try {
+        const result = await pool.query('DELETE FROM osint.assets WHERE id=$1', [id])
+        return (result.rowCount ?? 0) > 0 ? 'deleted' : 'not_found'
+      } catch (error) {
+        if ((error as { code?: string }).code === '23503') return 'in_use'
+        throw error
+      }
+    },
+
     async listNpcs() {
       const npcs = await pool.query<{ id: string }>('SELECT id FROM osint.npcs WHERE mystery_id IS NULL ORDER BY name')
       return (await Promise.all(npcs.rows.map(row => loadNpc(row.id)))).filter((npc): npc is NpcDto => npc !== null)