rename: nostrbook → nbread.lol (brand, domain, worker, repo)

[sovITxyz]

Full rebrand Nostrbook → nbread ("NOSTR BLOG READ"), migrating the live site to nbread.lol.

What changed

• Brand wordmark Nostrbook → nbread.lol across all views (header, hero, page-title suffixes, footer, docs/terms/privacy, README).
• Bare identifier nostrbook → nbread: worker name, package name, D1 database_name, health service string, markdown ruler id, cache header (X-Nbread-Cache), editor globals (NbreadDraft/NbreadEditorMd), and the nbread:preview-requested DOM event — synced across src, public/js, and tests.
• Domain nostrbook.net → nbread.lol: MAIN_HOST, routes/zone, NIP-05 (host-derived), all test host URLs, fixtures, docs. Routing/CSP/NIP-05 are host-agnostic (read MAIN_HOST), so no routing logic changed.
• Source links + repo → github.com/sovITxyz/nbread.
• Fixtures regenerated (re-signed) so event ids/sigs stay valid with the new content; deterministic keys/timestamps → npubs unchanged.
• Default relays: added relay.primal.net, nostr.wine, purplepag.es, relay.snort.social, nostr.mom (8 total). Dashboard relay textarea gains a helper surfacing the "add your own relays" flow.
• docs/setup.md §6 rewritten to separate reused live resources (D1/KV, kept by id) from the pending nbread.lol provisioning.

The Nostr protocol references (Nostr, nostr-tools, nostr.json, NIP-05/23, relay URLs) are deliberately untouched.

Verification

• tsc --noEmit clean
• 593/593 tests pass (vitest run)
• wrangler deploy --dry-run OK (bindings resolve: D1 nbread, MAIN_HOST=nbread.lol)
• Zero nostrbook occurrences remain
• Adversarial multi-agent review of prose/domain/docs consistency (1 confirmed prose nit fixed)

Follow-up (not in this PR)

• Provision the nbread.lol Cloudflare zone (DNS, wildcard SSL, Turnstile widget, WAF) and deploy the renamed worker — see docs/setup.md §6.
• Rename the GitHub repo to nbread.