usockets(win): defer READABLE re-arm past on_open so .end() mid-handshake doesn't hang - #30028

Now that `us_poll_stop` no longer does `p->uv_p->data = 0;`, the file-top comment above `poll_cb` ("uv_poll_t->data always (except for most times after calling us_poll_stop) points to the us_poll_t") is stale — the parenthetical exception no longer applies. The comments in `close_cb_free_poll`, `us_poll_free`, and `us_poll_stop` were updated to match the new behavior, but this one was missed; consider dropping the parenthetical.

Nit: this comment's last sentence ("The fix defers the READABLE re-arm until after on_open returns and skips it if on_open closed the socket") describes the context.c approach from 2dc4f5c/212d7e8/4782e95, which 1c3cbf9 reverted — context.c is no longer in the diff and `us_poll_change(READABLE)` at context.c:732 still runs *before* `on_open` on all platforms. The shipped fix is moving `uv_close` from `us_poll_stop` to `us_poll_free` so it runs from `check_cb` outside `poll_cb`; worth updating th