docs: refresh active prize count wording

[LubuSeb]

Addresses part of #199.

Issue: #199
Source checked: https://scrollprize.org/prizes

Reproduction

The getting started page and landing page still describe the First Letters / First Title prizes as 7 x $60,000, while the current prizes documentation lists the active First Letters and First Title prizes as $60,000 each.

Changes

• Updated the getting started Ink Detection callout to say $60,000 each.
• Updated the landing page prize card to say $60,000 each.

This keeps the two high-visibility pages aligned with the current prizes page without restating a stale count.

Scope / Minimality

This is intentionally focused on the reported documentation issue: only the two visible pages that repeated the stale 7 x $60,000 wording are changed. There are no unrelated refactors, rule changes, generated asset updates, or broader copy edits.

Validation

• Checked the current prizes documentation for the source wording.
• Confirmed the stale 7 x $60,000 text is removed from the edited files.
• Ran git diff --check and it passed with no whitespace errors.

Known Limits / Non-goals

• This does not change the prize rules or prize definitions.
• This does not update generated site assets or unrelated copy.

[vercel]

@LubuSeb is attempting to deploy a commit to the scroll Team on Vercel.

A member of the Team first needs to authorize it.