People search should match chosen and full/verified names

[michaelfransen]

🤖 Filed by Fizz, an AI agent, from a Buzz feature-request thread.

Problem

Buzz lets people choose expressive profile/display names, which is valuable, but
it makes coworkers difficult to find when someone only knows their real or
workplace name.

For example, searching for Jane Smith should find a coworker whose chosen
display name is night bee, without requiring the searcher to already know that
alias or the person's pubkey.

This affects every people-finding surface:

• global people search;
• @ mention autocomplete;
• DM recipient selection;
• channel member/add-people pickers.

Requested behavior

Keep user-chosen profile names expressive while making a separate human/full
name searchable:

• Let a person have both a chosen profile/display name and a human/full name.
• Match people queries against both values, case-insensitively and by substring.
• When the values differ, show both in results so the person can be
  disambiguated, for example night bee · Jane Smith.
• Use the same matching and result-label behavior across Desktop and Mobile.
• Continue treating the pubkey as canonical identity; neither name needs to be
  globally unique.

Prefer a single Full name field over requiring Western-style first/last
fields. In corporate communities, the existing relay-verified identity name can
serve as the authoritative full name. In communities without that identity
source, an optional self-supplied full name is a product choice.

Privacy and trust

• Do not make a new full-name value public outside its existing visibility
  boundary merely to support search.
• A relay-verified corporate name should remain distinguishable from
  self-supplied profile metadata.
• Search results should preserve the existing verified-name affordance when one
  is available.

Acceptance criteria

• A person with chosen name night bee and full/verified name
  Jane Smith is returned for searches matching night, Jane, or
  Smith.
• Global people search, mention autocomplete, DM recipient selection, and
  channel member pickers use the same multi-name matching behavior.
• Results show both names when they differ and retain the verified-name
  affordance where applicable.
• Exact duplicate labels remain distinguishable using existing identity
  metadata without changing pubkey identity.
• Desktop and Mobile have equivalent behavior.
• Tests cover chosen-name matches, full/verified-name matches, substring and
  case-insensitive matches, identical-name deduplication, and visibility
  boundaries.

Related work

• [Bug] Desktop profile conflates Nostr name with display name #2796 / fix(desktop): separate Nostr name from display name #3342 separate Nostr name from display_name in Desktop profile
  flows.
• feat(relay): add relay-verified identity binding #1476 adds relay-verified corporate identity names and displays the verified
  name alongside the chosen name.
• fix: member search matches substrings, not just prefixes #2529 adds substring matching to user-picker searches.
• feat(mobile): full-screen search with messages, channels, and people #402 added Mobile people search.

Those pieces establish the profile and search foundations, but none currently
defines consistent people-search matching across both the chosen name and the
human/verified name.

Source

Reported in Buzz channel buzz-feature-requests, thread event
1fb30784c0d990cab6fb4c0864a68d1d6590eddb132a662c1ce653e84135c610.