Add TMDB poster picker to film detail page

- New movie_images() async function in services/tmdb.py fetches poster
  URLs from TMDB /movie/{id}/images endpoint, filtering for English
  and no-text posters only
- New GET /tmdb/posters endpoint returns list of available posters for
  a TMDB ID
- New POST /films/{film_id}/poster endpoint to save selected poster
  (mirrors the stars endpoint pattern)
- Add "Change Poster" button on detail page (only shown if film has a
  TMDB ID) that opens a 3-column grid of posters
- Selected poster gets accent border, main image updates instantly, no
  page reload needed
- Posters are cached per load to avoid refetching on re-open

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/routers/tmdb.py b/routers/tmdb.py
index 522c1d0..5f7943f 100644
--- a/routers/tmdb.py
+++ b/routers/tmdb.py
@@ -3,7 +3,7 @@ from dotenv import load_dotenv
 from fastapi import APIRouter, Query
 from fastapi.responses import JSONResponse
 
-from services.tmdb import TMDBNotConfiguredError, search_movies
+from services.tmdb import TMDBNotConfiguredError, search_movies, movie_images
 
 load_dotenv()
 
@@ -30,3 +30,16 @@ async def search_tmdb(q: str = Query(..., min_length=2)):
                 "results": [],
             },
         )
+
+
+@router.get("/posters")
+async def tmdb_posters(tmdb_id: int = Query(...)):
+    try:
+        async with httpx.AsyncClient(timeout=10.0) as client:
+            urls = await movie_images(client, tmdb_id)
+        return {"posters": urls}
+    except TMDBNotConfiguredError:
+        return JSONResponse(
+            status_code=503,
+            content={"error": "TMDB_API_KEY is not configured.", "posters": []},
+        )