Cleanup: Removing monkeypatches for litegraph logic (#5902)

## Summary

Putting the litegraph specific pieces into litegraph itself, using the
CanvasGraph and LiteGraphGlobal to coordinate options.

This was one part of the Image Previews reloading/calculating with every
canvas draw.

## Review Focus

Is this keeping things decoupled enough?
Is this the right place to put things?
Are there assumptions about the options that I'm missing here?

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5902-WIP-Removing-monkeypatches-for-litegraph-logic-2816d73d3650818b860ec73579b89b54)
by [Unito](https://www.unito.io)

---------

Co-authored-by: github-actions <github-actions@github.com>

src/lib/litegraph/src/LGraphCanvas.ts

@@ -5194,10 +5194,9 @@ export class LGraphCanvas
     const color = node.renderingColor
     const bgcolor = node.renderingBgColor
 
-    const { low_quality, editor_alpha } = this
-    ctx.globalAlpha = editor_alpha
+    ctx.globalAlpha = this.getNodeModeAlpha(node)
 
-    if (this.render_shadows && !low_quality) {
+    if (this.render_shadows && !this.low_quality) {
       ctx.shadowColor = LiteGraph.DEFAULT_SHADOW_COLOR
       ctx.shadowOffsetX = 2 * this.ds.scale
       ctx.shadowOffsetY = 2 * this.ds.scale
@@ -5259,7 +5258,7 @@ export class LGraphCanvas
       }
     }
 
-    if (!low_quality) {
+    if (!this.low_quality) {
       node.drawBadges(ctx)
     }
 
@@ -5693,6 +5692,14 @@ export class LGraphCanvas
     ctx.globalAlpha = 1
   }
 
+  private getNodeModeAlpha(node: LGraphNode) {
+    return node.mode === LGraphEventMode.BYPASS
+      ? 0.2
+      : node.mode === LGraphEventMode.NEVER
+        ? 0.4
+        : this.editor_alpha
+  }
+
   #renderFloatingLinks(
     ctx: CanvasRenderingContext2D,
     graph: LGraph,
@@ -6044,7 +6051,7 @@ export class LGraphCanvas
   ): void {
     node.drawWidgets(ctx, {
       lowQuality: this.low_quality,
-      editorAlpha: this.editor_alpha
+      editorAlpha: this.getNodeModeAlpha(node)
     })
   }