feat(content): add TV Series content type with TMDB integration

Add complete TV series content surface: extraction from AI responses,
grid/detail views, TMDB TV search endpoint, and panel tab integration.
Includes film_ext-to-TV-series conversion for backward compatibility
and AI prompt instructions for [[tv_ext:...]] tags.

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

packages/app/src/composables/useImageFallback.ts

@@ -120,11 +120,12 @@ function escapeXml(s: string): string {
   return s.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;')
 }
 
-export async function fetchTmdbPoster(
+async function fetchTmdbGeneric(
+  endpoint: string,
   title: string,
   year?: number,
 ): Promise<TmdbResult> {
-  const key = cacheKey(title, year)
+  const key = `${endpoint}:${cacheKey(title, year)}`
   const cached = memoryCache.get(key)
   if (cached) return cached
 
@@ -132,7 +133,7 @@ export async function fetchTmdbPoster(
   try {
     const params = new URLSearchParams({ q: title.trim() })
     if (year && year > 0) params.set('y', String(year))
-    const res = await fetch(`/api/tmdb/search?${params}`)
+    const res = await fetch(`/api/tmdb/${endpoint}?${params}`)
     if (!res.ok) return empty
     const data = (await res.json()) as { posterUrl?: string | null; backdropUrl?: string | null }
     const result: TmdbResult = {
@@ -149,6 +150,13 @@ export async function fetchTmdbPoster(
   }
 }
 
+export async function fetchTmdbPoster(
+  title: string,
+  year?: number,
+): Promise<TmdbResult> {
+  return fetchTmdbGeneric('search', title, year)
+}
+
 export async function handleImgError(
   e: Event,
   title: string,
@@ -185,6 +193,13 @@ export function isUrlFailed(url: string | undefined): boolean {
   return !!url && failedUrls.has(url)
 }
 
+export async function fetchTmdbTVPoster(
+  title: string,
+  year?: number,
+): Promise<TmdbResult> {
+  return fetchTmdbGeneric('search-tv', title, year)
+}
+
 /** Fetch podcast artwork from iTunes Search API (free, no key). Returns hi-res URL (600x600). */
 export async function fetchPodcastCover(
   title: string,