Pricing: move Self-host $0 card BELOW paid tiers

The MIT-forever card at the top was tanking paid conversion —
a buyer landing on the page saw "$0 forever" as the first thing
and had no reason to keep scrolling to Pro/Team/Enterprise.

Reordered:
  1. Head + lede
  2. Paid tiers (Pro/Team/Enterprise) — the ask
  3. "Or run it yourself" → Self-host card — the fallback
  4. FAQ

Also demoted the self-host card:
  - Removed .featured highlight
  - Downgraded Download button to btn-secondary
  - Rewrote blurb so it reads as the free floor for solo/OSS
    users, not the default recommended path

Kept the OSS lede up top ("MIT-licensed"/"pay only when you want
us to run Postgres") — that's the honest anchor and buyers
respect it. What changed is the visual ordering of the CTAs.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>