fix(worker): release pending handlers after errors

[OskarEichler]

Fix

Release pending-call handlers after worker failures.

• Clear the pending map after the existing worker-error handler rejects outstanding calls.
• Remove the individual entry when postMessage throws synchronously, such as a DataCloneError. The Promise already rejects in this case, but the map currently retains its resolve/reject closures.

Before this change, a clone failure leaves one settled entry retained; two pending calls followed by a worker error leave two. Repeated failures accumulate these entries until termination or a reply that may never arrive.

No changes to search scoring, ranking, options, worker-error rejection scope, or public APIs. No breaking changes. This fixes cleanup only; it does not add worker restart/recovery behavior.

Verification

• All 449 existing tests across 22 files pass.
• All package builds, source type checking, lint, targeted formatting, and git diff --check pass.
• Inline checks cover 100 successive clone failures, worker-error rejection/cleanup, late replies, normal replies, remote errors, and termination. All settled-call checks leave the pending map empty.
• Failure reproduction uses a worker stub with real structuredClone validation; no real-browser worker lifecycle testing is claimed.
• No test files were added or changed.