feat: add work proof loop landing section

[Peter7896]

Summary

• add a Work Proof Loop landing-page section after the partner/logo band
• show funded-work examples with category, reward, deadline, required proof, and linked task CTAs
• explain the submission quality checklist and four-step review-to-wallet payout flow without adding dependencies or lockfile changes

Refs #100

Validation

• git diff --check
• npx tsc --noEmit --incremental false
• npm run build
• local desktop/mobile layout check: no mobile horizontal overflow

[vercel]

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