feat(world-2026): add programme page and speaker talk cards

[JessicaFerreiraLopez]

Summary

Adds the full Rails World 2026 Programme page and integrates each speaker's talk into their individual speaker page.

Programme page (/world/2026/programme)

• Tab navigation for Sept 23, Sept 24, reusing the existing faq-tab / faq-content-box / faq-panel components —
  straight borders, no rounding — so the schedule feels part of the same design system as the FAQ page
• Session cards use the neon gradient border pattern established across the site: a 0 0 0 1px $white spread shadow for the visible white border
  line, plus the directional neon outer glows and an inner glow via ::after
• Breaks and info-only sessions are filtered from the rendered list; social events with a location field (e.g. Closing Party, Community Game Night) render as simplified cards
• Responsive: reduced padding on tablet/mobile for both the page wrapper and individual cards

Speaker pages

• Replaced the static talk_title / talk_description frontmatter approach with a dynamic Liquid lookup against schedule.yml — a speaker's
  sessions are matched by checking session.speaker contains "First Last", so data lives in one place only
• Co-speaker talks (e.g. Alicia Rojas & Arely Rivera) appear on each speaker's individual page via the same contains match
• Date / time / track are rendered as glowing chips using border: 1px solid $white + @include neon-glow — scoped exclusively to .speaker-talks
  so the Programme page cards are unaffected

Test plan

• Visit /world/2026/programme — tabs switch correctly between Sept 23, Sept 24
• All 18 talk cards render with correct title, speaker, time, track, and description
• Private location sessions show "Private" label; public social events show venue name
• Visit a speaker page (e.g. DHH, Alicia Rojas, Aaron Patterson) — talk card(s) appear below bio with correct data
• DHH page shows both Opening Keynote and Matz & DHH session
• Neon glow chips (date/time/track) only appear on speaker pages, not on the programme page
• Nav shows "Programme" link on desktop and mobile
• Responsive: check programme page and speaker pages on mobile viewport