gpui: Fix dropped frames when scrolling an unfocused window (#61600)

Scroll events are delivered to the window under the pointer even when it
isn't focused, but we cap inactive windows at ~30fps to save energy, so
scrolling an unfocused window visibly drops frames. We now exempt
high-rate input from the cap using the existing `InputRateTracker`: a
trackpad scroll stream lifts it while events are arriving and for one
second after the last burst, then the cap resumes on its own.

## Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [ ] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

---

Release Notes:

- Fixed dropped frames when scrolling unfocused windows.

crates/gpui/src/window.rs

@@ -1589,13 +1589,16 @@ impl Window {
 
                 // Throttle frame rate based on conditions:
                 // - Thermal pressure (Serious/Critical): cap to ~60fps
-                // - Inactive window (not focused): cap to ~30fps to save energy
+                // - Inactive window (not focused): cap to ~30fps to save energy,
+                //   unless input is arriving at a high rate (e.g. scrolling an
+                //   unfocused window, which is delivered to the window under
+                //   the pointer).
                 let min_frame_interval = if !force_render
                     && !request_frame_options.require_presentation
                     && next_frame_callbacks.borrow().is_empty()
                 {
                     None
-                } else if !active.get() {
+                } else if !active.get() && !input_rate_tracker.borrow_mut().is_high_rate() {
                     Some(Duration::from_micros(33333))
                 } else if let Some(ThermalState::Critical | ThermalState::Serious) = thermal_state {
                     Some(Duration::from_micros(16667))
@@ -1638,7 +1641,7 @@ impl Window {
                 // to prevent display underclocking during active input.
                 let needs_present = request_frame_options.require_presentation
                     || needs_present.get()
-                    || (active.get() && input_rate_tracker.borrow_mut().is_high_rate());
+                    || input_rate_tracker.borrow_mut().is_high_rate();
 
                 if invalidator.is_dirty() || force_render {
                     measure("frame duration", || {