feat: stop using CSS filters for dark mode (static canvas) (#10578)

* feat: stop using CSS filters for dark mode (static canvas)

* fix comment

* remove conditional dark mode export

* make shape cache theme-aware

* refactor

* refactor

* fixes and notes

packages/excalidraw/css/styles.scss

@@ -106,6 +106,9 @@ body.excalidraw-cursor-resize * {
 
     &.interactive {
       z-index: var(--zIndex-interactiveCanvas);
+      // Apply theme filter only to interactive canvas for UI elements
+      // (resize handles, selection boxes, etc.)
+      filter: var(--theme-filter);
     }
 
     // Remove the main canvas from document flow to avoid resizeObserver
@@ -134,16 +137,6 @@ body.excalidraw-cursor-resize * {
     pointer-events: none;
   }
 
-  &.theme--dark {
-    // The percentage is inspired by
-    // https://material.io/design/color/dark-theme.html#properties, which
-    // recommends surface color of #121212, 93% yields #111111 for #FFF
-
-    canvas {
-      filter: var(--theme-filter);
-    }
-  }
-
   .FixedSideContainer {
     padding-top: var(--sat, 0);
     padding-right: var(--sar, 0);