fix: Vue Node <-> Litegraph node height offset normalization (#6966)

## Summary

Changes the layout store to treat node sizes as body-only measurements
while LiteGraph continues to reason about full heights. DOM-driven
updates are tagged with `LayoutSource.DOM`, which lets the store strip
the title height exactly once before persisting. That classification (a
new mutation source - `LayoutSource.DOM`) is accurate because those
mutations are triggered by the browser’s layout engine via
ResizeObserver, rather than by direct calls into the layout APIs (e.g.,
`moveNodeTo`, `useNodeDrag`). So all sources are:

- `LayoutSource.DOM`: browser layout/ResizeObserver measurements that
include the title bar
- `LayoutSource.Vue`: direct Vue-driven mutations routed through the
layout store
- `LayoutSource.Canvas`: legacy LiteGraph/canvas updates that will be
phased out over time
- `LayoutSource.External`: for multiplayer or syncing with a when going
online after making changes offline (in teams/workspace)

When layout state flows back into LiteGraph we add the title height just
in time for `liteNode.setSize`, so LiteGraph’s rendering stays
unchanged. This makes Vue node resizing and workflow persistence
deterministic - multiline widgets hold their dimensions across reloads
because every path that crosses the layout/LiteGraph boundary performs
the same normalization.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6966-normalize-height-at-sites-2b76d73d365081b6bcb4f4ce6a27663a)
by [Unito](https://www.unito.io)

---------

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

src/lib/litegraph/src/LGraphCanvas.ts

@@ -7,6 +7,7 @@ import { getSlotPosition } from '@/renderer/core/canvas/litegraph/slotCalculatio
 import { useLayoutMutations } from '@/renderer/core/layout/operations/layoutMutations'
 import { layoutStore } from '@/renderer/core/layout/store/layoutStore'
 import { LayoutSource } from '@/renderer/core/layout/types'
+import { removeNodeTitleHeight } from '@/renderer/core/layout/utils/nodeSizeUtil'
 
 import { CanvasPointer } from './CanvasPointer'
 import type { ContextMenu } from './ContextMenu'
@@ -4043,16 +4044,25 @@ export class LGraphCanvas
 
     // TODO: Report failures, i.e. `failedNodes`
 
-    const newPositions = created.map((node) => ({
-      nodeId: String(node.id),
-      bounds: {
-        x: node.pos[0],
-        y: node.pos[1],
-        width: node.size?.[0] ?? 100,
-        height: node.size?.[1] ?? 200
-      }
-    }))
+    const newPositions = created
+      .filter((item): item is LGraphNode => item instanceof LGraphNode)
+      .map((node) => {
+        const fullHeight = node.size?.[1] ?? 200
+        const layoutHeight = LiteGraph.vueNodesMode
+          ? removeNodeTitleHeight(fullHeight)
+          : fullHeight
+        return {
+          nodeId: String(node.id),
+          bounds: {
+            x: node.pos[0],
+            y: node.pos[1],
+            width: node.size?.[0] ?? 100,
+            height: layoutHeight
+          }
+        }
+      })
 
+    if (newPositions.length) layoutStore.setSource(LayoutSource.Canvas)
     layoutStore.batchUpdateNodeBounds(newPositions)
 
     this.selectItems(created)