Adds the client-side half of the user-search endpoint landed
on the server in b3056f1c (commit 6 on this branch). The
client mirrors the server's filter contract:
- query: substring match on FullName or UserName
- email: exact match on Email
- take: 1..100, default 25
Empty (query + email) short-circuits to an empty list
client-side rather than letting the server return the first
`take` users alphabetically — the address-book UX is
"type to search", not "show me a directory".
The DTO (Yavsc.Api.Client.Dtos.UserSearchResultDto) is a flat
shape (Id, UserName, FullName, Avatar, Email) with no
navigation properties; field names match the JSON the server
emits so deserialisation is a no-op.
PostIt wiring:
- App.axaml.cs constructs a UserSearchClient singleton and
registers it alongside CircleApiClient and BlogAclApiClient.
- The PostIt.csproj ProjectReference to Yavsc.Api.Client was
in place before this commit on feat/postit-acl; the rebase
of feat/app-invite on top of feat/postit-acl dropped it.
This commit re-adds it.
