feat(search): cache and expose last search parameters for replay and context retrieval

- Add methods to save and retrieve last search parameters in SearchChain
- Persist search params alongside results for replayable search context
- Add /last/context endpoint to fetch last search results and parameters
- Update tests to cover search param caching logic
- Allow images.tmdb.org in SECURITY_IMAGE_DOMAINS

app/core/config.py

@@ -486,6 +486,7 @@ class ConfigModel(BaseModel):
     SECURITY_IMAGE_DOMAINS: list = Field(
         default=[
             "image.tmdb.org",
+            "images.tmdb.org",
             "static-mdb.v.geilijiasu.com",
             "bing.com",
             "doubanio.com",