fix(ui): bound OpenCode read requests so half-open sockets cannot freeze bootstrap (#2470)

The SDK client fetch wrapper now applies a 30s timeout to non-streaming
reads. Without it, a socket that neither resolves nor rejects keeps the
directory bootstrap concurrency slot busy forever and the UI stays on
"loading sessions". Long-lived streams (POST prompts, the /event SSE)
are explicitly excluded so they are not cut off mid-flight.

The normalized "request timed out" error is added to the retry
allowlist alongside undici's "terminated" (the exact failure observed
in #2470 when undici tears down a half-open upstream connection); both
are transient while the managed OpenCode process restarts. Caller-
initiated aborts keep their original error shape so a user-cancelled
request is not retried.

Tests cover: GET timeout fires after the bound, POST is not timed out,
/event SSE is not timed out, caller abort wins, AbortError is not
retried, and the SDK normalized error is retried 3x.

packages/ui/src/sync/retry.ts

@@ -6,6 +6,10 @@ export interface RetryOptions {
   retryIf?: (error: unknown) => boolean
 }
 
+// undici tears down half-open upstream connection with `TypeError: terminated`
+// (exact failure from the #2470 logs); the SDK client also rejects reads with
+// normalized "request timed out" error after OPENCODE_REQUEST_TIMEOUT_MS.
+// Both are transient — managed process may be restarting.
 const TRANSIENT_MESSAGES = [
   "load failed",
   "network connection was lost",
@@ -18,6 +22,8 @@ const TRANSIENT_MESSAGES = [
   "opencode api unavailable",
   "503",
   "502",
+  "terminated",
+  "request timed out",
 ]
 
 function isTransientError(error: unknown): boolean {