Add timeout protection to prevent indefinite hangs when Urbit server
becomes unresponsive or network partition occurs.
Changes:
- Add AbortSignal.timeout(30_000) to 7 one-shot fetch calls
- Add AbortController with 60s connection timeout to SSE stream fetch
(clears timeout after headers received to avoid aborting active stream)
Affected methods: sendSubscription, connect, openStream, poke, scry, close
Fixes#5266
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
411d5fda58