copy(deep + blogs): retire the remaining fear-coded language (#115)

Phase 3 of the renewed-voice arc: surgical lighter-touch pass on deep
pages + blog catalog. Front door was Phase 1–2; this closes the trail.

Marketing copy (marketing.ts)
- tagline.sub "Proof, so you never have to fight to be believed." →
  "Proof, ready before anyone asks." (also feeds Margin's brain)
- trustModel.subtitle "take on faith" → "argue about" (tribe-marker
  retired; rhymes with the home thesis)
- trust…