/// Returns the current time in milliseconds.
///
/// Reads `Date.now()` through `js_sys` rather than the DOM high-resolution
/// clock, because the web-sys `Performance` feature is not enabled for this
/// crate. Millisecond resolution is sufficient here: the only threshold it
/// feeds is `long_press_millis`, whose default is two orders of magnitude
/// larger than the clock's granularity.
///
/// Off-wasm the JS runtime is absent, so the monotonic host clock is used
/// instead. That keeps the state machine testable on the host, where a real
/// `touchstart` can never occur anyway.
///
/// # Returns
///
/// - `f64` - Milliseconds since the Unix epoch, or `0.0` if the clock is
/// unavailable.
pub