DB-first library reads, mixed library indexing, and manual NFO refresh

- API reads now serve from media_items cache instead of scanning the filesystem
  on every request; scans (manual or scheduled) remain the write path
- NFO metadata is no longer parsed automatically during scans; title falls back
  to folder/filename — metadata can be refreshed per-item via the kabob menu
- Mixed libraries are now indexed in media_items (new mixed_file item type)
  with file_path stored; scanMixed walks recursively and upserts all files
- Added file_path column to media_items and migrated item_type CHECK constraint
  to include mixed_file via safe table-recreation migration
- New POST /api/nfo-refresh endpoint reads the .nfo for a single item and
  patches its DB row (supports movie, tv_series, tv_episode)
- Added "Refresh metadata" button to movie and TV series kabob menus

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/api/tv/route.ts

@@ -2,7 +2,7 @@ import fs from 'fs'
 import path from 'path'
 import { NextRequest, NextResponse } from 'next/server'
 import { getLibrary, resolveLibraryRoot, resolveAndJail } from '@/lib/libraries'
-import { scanTvLibrary, scanTvSeasons, scanTvEpisodes } from '@/lib/tv'
+import { tvSeriesFromDb, tvSeasonsFromDb, tvEpisodesFromDb } from '@/lib/tv'
 import { removeAllAssignmentsForItem } from '@/lib/tags'
 import { requireLibraryAccess, requireAdmin } from '@/lib/auth'
 
@@ -27,20 +27,15 @@ export async function GET(request: NextRequest) {
     return NextResponse.json({ error: 'Library is not a TV library' }, { status: 400 })
   }
 
-  const root = resolveLibraryRoot(library)
-
   if (seriesId && seasonId) {
-    const episodes = scanTvEpisodes(root, libraryId, seriesId, seasonId)
-    return NextResponse.json(episodes)
+    return NextResponse.json(tvEpisodesFromDb(libraryId, seriesId, seasonId))
   }
 
   if (seriesId) {
-    const seasons = scanTvSeasons(root, libraryId, seriesId)
-    return NextResponse.json(seasons)
+    return NextResponse.json(tvSeasonsFromDb(libraryId, seriesId))
   }
 
-  const series = scanTvLibrary(root, libraryId)
-  return NextResponse.json(series)
+  return NextResponse.json(tvSeriesFromDb(libraryId))
 }
 
 export async function DELETE(request: NextRequest) {