fix(tui): forward directory-scoped events when TUI is in workspace mode (#26671)

The TUI's useEvent filter returned early in the workspace branch when the
inbound event's workspace did not match the TUI's active workspace —
including the common case where event.workspace was undefined because the
session has no workspaceID. The early return meant directory-scoped
events from external POSTs (web UI, SDK, curl) targeting a session
running in the same directory were silently dropped, even though the
server published them correctly with the right directory.

Treat events without a workspace label as directory-scoped and fall
through to the directory comparator so the TUI re-renders them. Also
adds an explicit return after the global-event handler so a global event
isn't forwarded twice.

Test cases (a)-(c) in httpapi-promptasync-events.test.ts now all forward;
(d) keeps cross-workspace events dropped.

https://claude.ai/code/session_011VwDFG5W32dnu1qnT3SGr1