Reconcile scraper sources list: code vs docs

[Railly]

Context

trigger/scrapers/sources ships 9 scrapers (devpost, eventbrite, exa, hackathon-com, haiku, meetup, mlh, perplexity, universities); docs/product-scope.md and lib/scraper/SCRAPER_EVALUATION.md may list a different set.

Task

Diff docs against code, update the docs, and note any dead scrapers.

Acceptance criteria

Docs enumerate exactly the sources that exist, with status.

[linear]

HCK0-107

[slegarraga]

Happy to take this one. I will diff the scraper source list against the docs, update the docs, and note any dead sources.