BUD-01 defines a Blossom URL as `<server>/<sha256>[.<ext>]` — the blob hash is
always the last path segment. Walking the path right-to-left for any hex
match was too permissive: a non-Blossom URL like `https://example.com/<sha>/avatar.jpg`
(sha appears in an intermediate segment) would get incorrectly bridged.
Both parsers now look at the last path segment only and skip the URL entirely
when it isn't a sha256. The earlier hex-prefix case (share.yabu.me's
`<cache-prefix>/<blob>.ext`) still works because the blob is still the last
segment; the prefix flows into `xs` via the existing `buildServerBase` /
`extractServerBase` logic. Adds negative tests covering the
sha-in-non-last-segment case in both modules.
Claude
3cc9ac8b7c