test(transport): cover accepted server identity formats

[1amKhush]

Problem

parseServerIdentity accepts three externally supplied identity formats—hex pubkeys, npub, and nprofile—but currently has no focused unit tests. A regression here can prevent the client transport from starting or silently discard relay hints.

Scope

Add src/transport/nostr-client/server-identity.test.ts covering:

• a valid 64-character hex pubkey;
• uppercase or mixed-case hex if supported by the existing contract;
• a valid npub identity;
• a valid nprofile identity with relay hints;
• an nprofile without relay hints;
• malformed, unsupported, and empty input;
• the stable transport-facing error message for invalid input.

Use nostr-tools encoders to build valid Bech32 fixtures rather than hard-coding opaque values where practical.

Non-goals

• Do not add new identity formats.
• Do not change relay discovery or connection behavior.
• Keep production changes out of scope unless a test exposes a confirmed defect.

Acceptance criteria

• Tests exercise all three documented input formats and the common error path.
• Tests are deterministic and make no relay or network calls.
• Existing tests, lint, and type checking continue to pass.

Verification

bun test src/transport/nostr-client/server-identity.test.ts
bun lint
bun typecheck