Feat/answer link transformation

[sabinem]

A participant pastes their GitHub URL into a registration answer, and now anyone reading that answer can click it.

Before, they couldn't. Registration questions of the free-text kind are where people put an address — their repo, their portfolio, the paper they'd like to build on — and the answer was printed as flat text everywhere it appeared. An organizer going through fifty sign-ups had to select each URL and copy it into the address bar, one at a time. So did a participant reading a teammate's shared answers.

Answers now render through a single component. Text stays text; anything that is an http:// or https:// address becomes a link that opens in a new tab.

Details:

• Four places changed, all of them reading the same component: your own profile and a peer's shared answers, the organizer's view of a single participant, and both lists on the organizer's registration-answers page (the folded "who said what" and the open free-text list). Previously each of these had its own copy of "print the value, saying Yes/No for a tick-box"; that logic now lives in one place.
• The address as typed is also the visible text. Deliberate — it means an answer cannot show yourbank.com while pointing somewhere else, which is exactly the trick a linkifier that accepted a separate label would hand to anyone filling in a form.
• Only http and https. Not "other schemes are rejected" but "other schemes are never candidates" — the matcher only looks for those two, so javascript:, data: and file: stay as the text they are.
• No {@html} anywhere. The splitter returns a list of segments and Svelte renders and escapes them, so an answer containing <script> appears on the page as those characters. This is why the answers do not go through the existing markdown pipeline, even though it would have linkified them for free — see below.
• Trailing punctuation goes to the sentence, not the URL: see https://x.dev/a. links without the full stop, and (https://en.wikipedia.org/wiki/Foo_(bar)) keeps its inner parens and drops the outer one.
• Two of the four views put the answer in a flex flex-wrap row, where a flex item won't shrink below its content — a long pasted URL would have widened the whole row. They gained min-w-0 break-words.

Deliberately left out:

• Markdown. Running answers through the app's existing markdown renderer would have made links clickable with almost no code, but nobody has told participants their answer is markdown — there's no editor, no help text, no preview. An answer of 5 * 3 * 2 = 30 would come out with emphasis in it, and a line beginning # 1 pick would become a heading. Organizer-written page content is markdown because its author knows it is.
• Bare www.example.com and email addresses. Considered and dropped in favour of the narrowest rule that has no false positives. Easy to add later if people ask.
• The CSV export is untouched — a URL there stays a plain string, which is what a spreadsheet wants.
• The registration form says nothing about links. A pasted link just works, and a hint invites people to wonder what other formatting is on offer when the answer is "none".
• Enum and boolean answers pass through the same component, where it's a no-op. One rule for how an answer prints beat two.