Scope redraw requests and avoid redundant animation fallback wakeups

Instrument redraw sources, per-output request coalescing, and animation fallback scheduling. Route local visual changes to their affected outputs while preserving deferred grab and gesture updates.

Schedule fallback recovery using each orphaned animation output's refresh interval, suppress it while a normal frame chain exists, and retain requested final frames after scheduling failures. Add mixed-refresh, cursor footprint, frame-chain, and disconnect regressions and document measurement limits.

compositor/src/cursor.rs

@@ -14,6 +14,7 @@ const DEFAULT_CURSOR_SIZE: u32 = 24;
 pub(crate) struct NamedCursor {
     pub buffer: MemoryRenderBuffer,
     pub hotspot: Point<i32, Buffer>,
+    pub size: Size<i32, Buffer>,
 }
 
 pub(crate) fn cursor_theme() -> CursorTheme {
@@ -74,6 +75,7 @@ fn cursor_from_image(image: Image) -> NamedCursor {
     NamedCursor {
         buffer,
         hotspot: Point::from((image.xhot as i32, image.yhot as i32)),
+        size,
     }
 }
 
@@ -103,6 +105,7 @@ fn fallback_cursor() -> NamedCursor {
             None,
         ),
         hotspot: Point::default(),
+        size: (WIDTH as i32, HEIGHT as i32).into(),
     }
 }