Add NamecoinLookupException sealed class to distinguish:
- NameNotFound: name queried successfully but doesn't exist on blockchain
- NameExpired: name exists but expired (>36000 blocks since last update)
- ServersUnreachable: all ElectrumX servers failed with connection errors
Previously, all three cases returned null from nameShowWithFallback,
making it impossible for the UI to show meaningful feedback.
Changes:
- ElectrumxClient.connectAndQuery: throws NameNotFound/NameExpired
instead of returning null for definitive blockchain answers
- ElectrumxClient.nameShow: lets NamecoinLookupException propagate
(only catches connection/IO errors as null)
- ElectrumxClient.nameShowWithFallback: short-circuits on NameNotFound/
NameExpired (no point trying other servers for definitive answers),
throws ServersUnreachable when all servers fail with connection errors
- SearchBarViewModel: new namecoinSearchState flow with typed states
(Idle/Loading/Resolved/NotFound/Expired/ServersUnreachable) for UI
to show loading spinners, resolved profiles, and specific error
messages. Derived namecoinResolvedUser from this flow.
Discovered while porting to notedeck (damus-io/notedeck#1314).
M
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