Add profile page rendering and relay hints

[alltheseas]

Pre-requisites

Requires relay pool #38 in order to work.

Summary

Adds full Damus-style profile rendering and relay-hint ingestion on top of the
existing async client, without touching the shared relay pool work.

• Serve the Damus frontend assets from src/main.rs: /damus.css, /
  fonts/PoetsenOne-Regular.ttf, embedded default avatar/logo, and a
  new homepage (html::serve_homepage). Profile requests now feed into
  html::serve_profile_html, and once we’ve resolved a profile note we spawn
  render::fetch_profile_feed to hydrate recent notes via the existing per-
  request nostr-sdk client.
• src/html.rs gains the full profile layout: banner, metadata rows (npub/
  nip05/website/LUD16), recent note cards, relay list accordion, and CTA
  buttons. It also introduces an HTML landing page and helper scripts for
  local-time rendering and npub copying.
• src/render.rs reworks profile fetching for the standalone client—collects
  relay hints from kind:10002 and kind:3, streams recent notes (with lookback
  fallback), and waits for nostrdb ingestion before rendering. No persistent
  relay pool wiring is included here.
• Bundles the styling assets (assets/damus.css, assets/logo_icon.png, fonts/
  PoetsenOne-Regular.ttf) and whitelists the font in .gitignore.