Home hero: add suggested-question chips below the assistant prompt

Design review follow-up from https://github.com/clevercanary/cc-design/issues/333 (Ask 1). The designer's first recommendation on the hero:

> I would add some suggestions under the search bar to encourage exploration

This also restores something from the original home-page design: #1300 specified an "Ask anything…" assistant input **with quick-action chips**, and the chips were dropped from the build in #1690.

## Scope

A row of suggested-question chips directly beneath the hero prompt (`sites/brc-analytics/views/HomeView/components/SectionHero/`), styled and spaced per the Figma in the design ticket.

- Chips are a small fixed set of starter questions, defined as a constant beside the hero (no fetching, no personalisation).
- Clicking a chip opens the assistant with that question as the first message — the same destination a typed question reaches. Reuse `getAssistantUrl`/`getAssistantHref` from `components/AssistantPrompt/hooks/UseAssistantPrompt/utils.ts` rather than rebuilding the URL, so both paths stay identical.
- Decide and document one behaviour: chip navigates straight to the assistant (recommended, matches the typed path) vs. chip fills the input and leaves the user to submit. Don't do both.
- Keyboard and screen-reader accessible: real links/buttons, focus visible, sensible order after the input.
- Wrap sanely at narrow widths — chips are part of the hero's responsive behaviour (see the hero responsive ticket).
- Copy for the questions needs a pass from the team; seed with the ones in the designer's mockup.
- BRC only.

## Acceptance criteria

- Suggested-question chips render beneath the hero prompt, matching the Figma.
- Activating a chip opens the assistant pre-loaded with that question, identical to typing it.
- Chips are reachable and operable by keyboard, and wrap without overflowing at mobile widths.