feat(zap): render zap messages as mini-posts in the engagement drawer

[dmnyc]

Summary

Zap messages used to render as a single truncated line in the
engagement drawer and a raw URL on the top-zap banner. That worked
for short "thanks!" zaps but mangled longer messages — anything with
body text + a link + an image got chopped to `...tes…` and the
content was lost.

This PR treats the two surfaces differently to suit their constraints:

• Engagement-drawer zap row — rewritten as a mini-post. Avatar +
  display name + private icon + bolt + sats in a header row, then
  the message body renders through the same `RichContent` pipeline a
  regular kind-1 post body uses. Inline images, hashtags, profile /
  note mentions, plain links with OG preview cards, all rendered the
  same as in the feed. Body is not truncated; row grows vertically.
• Top-zap banner above the post action bar — still a one-line
  preview. Image URLs collapse to the literal `[image]` token via a
  small `ZapMessageImage` helper so the sats amount stays visible.
• Cross-platform parity doc `ZAP_IMAGE_PARITY.md` describes the
  contract for the iOS agent — banner uses the URL-collapse helper,
  drawer delegates to the iOS post-body renderer.

`eventRepo` is plumbed from `ReactionDetailsSection` into `ZapRow` so
the rich-content pipeline can resolve profile mentions / quoted
notes from cache.

Test plan

• Zap a post with `"thanks!"` — drawer row renders just the
  single-line text below the header (no body wrap, no card).
• Zap with `"check this out https://nostr.com"\` — drawer row
  shows the body, with an OG preview card for nostr.com below.
• Zap with an image URL only (e.g. `https://i.nostr.build/x.gif\`)
  — drawer row body renders the inline image; top-zap banner
  shows `[image]`.
• Zap with body + image URL — drawer renders body text + inline
  image; top-zap banner shows `text [image]` (or
  `[image] text`).
• Zap with a long (400-char) body — drawer row grows vertically;
  nothing is truncated; sats amount stays visible in the header.
• Long-press a drawer zap row → existing `ZapInspectorDialog`
  still opens.
• Tap the row header (anywhere outside body links) → routes to
  zapper's profile.
• Tap an OG card or link inside the body → opens browser.
• Zap with a `nostr:nevent1...` reference in the body — renders
  as a quoted note card inside the zap row.