Conditional GET plus an RSS-first, Atom-fallback parser normalising both
into one entry model, with iTunes explicit and ttl handling carried over
from the Python. Enclosures are recorded as pending; nothing downloads yet.
GUID falls back guid -> link -> enclosure url -> title rather than hashing
the description as the original did.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RPyeapneuXrCdojsaiXGbe
