fix(cards): parse HTML release-feed tables before generating Bluefin cards

[castrojo]

Problem

scripts/lib/card-feed-parser.mjs accepts only Markdown tables, while the Bluefin and Bluefin LTS release feeds contain HTML tables.

Evidence

node scripts/generate-card-images.mjs logs no release found and skips both Bluefin slugs, generating only Dakota card images.

Expected

Parse the HTML release-table representation in addition to Markdown and cover it with a real feed fixture.