fix(downloads): a suspended user's queued jobs wait, and a clip too big for the space left says so

A suspension now blocks the user's downloads as quota.resolve already advised: the worker leaves
their queued jobs unclaimed until it is lifted (the confirm says so). A cut clip larger than the
remaining storage is refused with its own message (not "storage is full"), and a clip's quota
refusal reads as a clip's in both languages. The cancel poll compares to JobStatus.RUNNING.

backend/tests/test_download_errors.py

@@ -63,6 +63,7 @@ def test_our_own_worker_refusals_classify_as_themselves():
     # fragment of the text. Pinning message and rule together is what stops an edit to the wording
     # from silently orphaning the category — the UI would then fall back to "Download failed".
     assert classify(dlerrors.QUOTA_FULL_MESSAGE) == "quota_exceeded"
+    assert classify(dlerrors.CLIP_TOO_BIG_MESSAGE) == "quota_exceeded"
 
 
 def test_the_redacted_network_text_classifies_back_to_network():