feat(web): surface jury round phase countdown

[sebas11042]

Summary

This PR updates the web jury/dashboard UI so users can clearly understand the current sealed round phase and how long remains until the configured Drand reveal round R.

It adds a dedicated round phase classifier for the UI, surfaces an explicit Open / Reveal / Settled phase badge, and shows a live reveal countdown tied to the target Drand round. The countdown also handles rounds where R has already passed, which is important for the bundled offline demo fixture because its canonical trace is already settled.

Closes #155

What Changed

• Added classifyRoundPhase for UI-level phase classification:

  • Open when the round is still waiting for Drand R
  • Reveal when the round is revealing, cleared, or Drand R has already published
  • Settled when the round is terminal, including settled or voided rounds

• Updated the round status card in apps/web to display:

  • A visible phase badge: Open, Reveal, or Settled
  • The existing contract round status
  • A dedicated Phase row
  • A dedicated Reveal countdown row

• Improved Drand countdown behavior:

  • Uses the live Drand quicknet info when available
  • Falls back to local quicknet timing when offline or when the Drand request fails
  • Correctly displays when the target round R has already published

• Added component-level coverage for the round status card:

  • Settled round with past Drand R
  • Open round with future Drand countdown
  • Open round where Drand R has already passed and should surface as Reveal

Why

Before this change, users could see raw round/Drand information, but the jury UI did not clearly communicate the actual product-facing phase of the round or make the reveal timing obvious at a glance.

This is important because the core user flow depends on understanding when sealed values become revealable.

Offline Demo Behavior

The bundled dashboard fixture still works without a configured live endpoint. Since the fixture is already settled and its Drand round is in the past, the UI now shows that R has already published instead of relying on a live Drand request.

Tests

Ran successfully:

npx.cmd pnpm@10.13.1 web:test
npx.cmd pnpm@10.13.1 web:typecheck
npx.cmd pnpm@10.13.1 web:build

## Test result:
web:test: 48/48 passing
web:typecheck: passing
web:build: passing