feat(onboarding-email): new PauseAI UK welcome emails

[UFO-101]

What

Replaces both PauseAI UK welcome emails in the UK override with the copy the chapter now sends, ported from two MailerSend test sends by the chapter's director on 2026-09-15. Volunteers get the version that asks them to join WhatsApp up front; everyone else gets the version that mentions WhatsApp only in the footer. Both stay in the plain layout.

Decisions

• Every UK link is fixed in code (WhatsApp, events calendar, intro call, campaigns page, socials) at the chapter's request. The UK section no longer reads the National Groups row, so updating a link is an edit to chapterOverrides.ts.
• The events list is dated. Nothing checks the date, so each of the three events (26 Sep, 20 Oct, 5 Dec) has to be removed once it has happened. They sit in one clearly marked array at the top of the UK section.
• The lobby-day sentence links Luma directly. The chapter's email used a CiviCRM click-tracking redirect that resolves to the same Luma page.
• The confirm line and the newsletter line are the skeleton's fixed copy, as for every override.

Renderer changes

• A newline inside a block's text now becomes <br> in HTML (markdown.ts), so "RSVP here" sits under each event and the signature stacks as two lines.
• The plain-text renderer now strips **bold** from list items (text.ts), matching what it already did for paragraphs. No existing copy used bold in a list.

Tests

The test that checked a row link carrying its own markdown is untouched now moved from the UK to Sweden, which still splices row links into a sentence. New assertion for two-line list items.

How verified

• vitest run src/lib/server/onboardingEmail: 18 passed.
• eslint clean; svelte-check reports no errors in the changed module.
• Both versions rendered end to end through renderOnboardingEmail and compared against the source emails.
• To eyeball: /onboarding-email-preview on the deploy preview, which defaults to United Kingdom / Volunteer.

🤖 Generated with Claude Code

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