fix(desktop): find profileless users by pubkey

[alebairos]

Summary

Allow Desktop channel member search to resolve an exact 64-character hex
pubkey or exact npub even when that community member has no kind-0 profile.

Exact identity queries now fetch the profile event and NIP-43 membership
snapshot together. Profile metadata is preserved when present; otherwise a
bare-key candidate is returned only when the identity is in the community
roster. Existing full-text profile/name search remains unchanged.

The client-side candidate ranker also recognizes canonical npub values so the
exact backend result is not filtered out before display.

Related issue

N/A. No matching open issue or pull request was found.

Testing

• just ci
  • workspace formatting and strict Clippy
  • repository unit suites
  • Desktop checks, full tests, production build, and Tauri checks
  • web checks and production build
  • mobile analysis and full tests (875 passed, 1 skipped)
• Desktop native suite: 1,855 passed, 14 ignored
• Desktop mixer diagnostics: 3 passed
• Regression tests cover exact hex, exact npub, a profile-less NIP-43 member,
  non-member rejection, open-relay fallback, and client-side npub ranking.
• Physical HITL test against wss://buzz.alebairos.xyz:
  • exact hex lookup found and added the profile-less Android identity;
  • exact npub lookup found and added the same identity;
  • independent channel-roster queries confirmed membership in both test
    channels.

There is no visual layout change, so before/after screenshots are not
applicable. Post-invite profile editing remains a separate follow-up.

[Chessing234]

handy for bare keys. please make sure a typo of 63 hex chars still falls through to normal search and doesnt error the whole picker

[alebairos]

Confirmed: exact-key lookup requires exactly 64 hex characters (or a valid npub). A 63-character hex typo returns None from exact parsing and continues through the existing NIP-50 search path.