Add review velocity landing-page section

[zxh920310-cpu]

Related Issue
Closes #130

What changed

• Added a ReviewVelocity landing-page section that explains how creators and contributors can keep funded work reviewable.
• Calls out clear requirements, reviewable proof, review cadence, and approval readiness.
• Places the section between the "Looking for" tabs and testimonials so it supports both creator and contributor flows.

Why
Issue #130 asks for a focused section that sets clearer submission and approval expectations for funded work.

How tested

• Not run locally; change is limited to a static landing-page component and homepage composition.

Known limitations

• No screenshots included because this environment did not install or run the Next.js app.

Bounty note
This PR addresses the GitHub issue only. No external platform signup, wallet, or payment details are included.

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