[codex] Polish Nostr npub profiles and statistics

[guaka]

What changed

• Shows a NIP-05 style Nostr address on profiles with saved npubs, while keeping njump links.
• Canonicalizes saved npubs, rejects npubs already used by another account, and adds a partial unique index for non-empty npubs.
• Adds Nostr to public network statistics and updates related client/server tests.
• Keeps NIP-05 fail-closed behavior covered for malformed stored keys.

Issue bundle

Refs #2699, #2700, #2710.

#2693 is covered by the existing Nostr-only profile rendering test, now updated for NIP-05 display. #2716 was checked during implementation: https://trustroots.org/.well-known/nostr.json?name=bobgle returns {"names":{}} rather than a 502.

This intentionally does not include #2718 proof-of-control or #2669 import/export forkability work.

Deployment note

Before enforcing the new partial unique index in production, check for existing duplicate non-empty nostrNpub values and resolve them intentionally; this PR does not silently change existing user data.

Validation

• npm run test:client -- modules/users/tests/client/components/ProfileViewBasics.tests.js
• npm run test:client -- modules/statistics/tests/client/components/Statistics.component.tests.js
• npm run test:client
• Targeted server suite for profile, statistics, and NIP-05 routes: 111 passing
• Focused statistics route server test: 4 passing
• npm run test:server:codex: 1326 passing, 34 pending
• ESLint on all touched files passed; full npm run lint was attempted but did not complete after several minutes, so it was stopped.