test: stub ctx gains the auth_token key run_download now reads

The real phase-1 ctx has always carried auth_token; the native branch now
threads it into the adapter constructors, so the stub ctx must match the
contract (kept the strict ctx[...] read — it catches exactly this drift).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CDgx8bQS5YrGRK76v8HUnM

tests/test_download_service.py

@@ -322,7 +322,7 @@ async def test_run_download_native_resolves_vanity_and_runs(
     ctx = {
         "platform": "patreon",
         "source_id": source.id, "url": "https://patreon.com/alice",
-        "artist_slug": "alice", "cookies_path": None,
+        "artist_slug": "alice", "cookies_path": None, "auth_token": None,
         "config_overrides": {},
     }
     result, resolved = await db_mod.run_download(
@@ -355,7 +355,7 @@ async def test_run_download_native_unresolvable_fails_loud(
     ctx = {
         "platform": "patreon",
         "source_id": source.id, "url": "https://patreon.com/alice",
-        "artist_slug": "alice", "cookies_path": None,
+        "artist_slug": "alice", "cookies_path": None, "auth_token": None,
         "config_overrides": {},
     }
     result, resolved = await db_mod.run_download(