`validation.py` had amazon absent from `_streaming_sources`, causing
Amazon TrackResult objects (bitrate=None, size=0) to fall through to
the Soulseek P2P code path and get rejected by
`filter_results_by_quality_preference`. Every album track was marked
not found.
Fix: add 'amazon' to every streaming-source guard tuple/set that was
previously missing it:
- core/downloads/validation.py — primary bug fix (quality-filter bypass)
- core/downloads/status.py — _STREAMING_SOURCE_NAMES frozenset
- core/downloads/task_worker.py — hybrid fallback client map
- core/imports/side_effects.py — || filename→stream-id extraction
- web_server.py — is_streaming_source, transfer list display,
candidate source label, _try_source_reuse, _store_batch_source
- tests/test_download_plugin_conformance.py — registry count + parametrize
Also updates the 2.5.3 What's New entry to drop the stale
"not yet wired" disclaimer.
791e3630ff