Cleanup: YAGNI readonly props, private swap on ComfyApp, Canvas resize events simplification, v-memos on individual instances (#5869)

## Summary

Assorted cleanup opportunities found while working through the Vue node
rendering logic cleanup.

## Review Focus

Am I wrong that the readonly logic was never actually executing because
it was defined as False in GraphCanvas when making each LGraphNode?

Is there an edge case or some other reason that the ResizeObserver
wouldn't work as a single signal to resize the canvas?

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5869-Cleanup-YAGNI-readonly-props-private-swap-on-ComfyApp-Canvas-resize-events-simplificat-27e6d73d3650811ba1dcf29e8d43091e)
by [Unito](https://www.unito.io)

---------

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

tests-ui/tests/renderer/extensions/vueNodes/components/NodeHeader.subgraph.test.ts

@@ -131,20 +131,6 @@ describe('NodeHeader - Subgraph Functionality', () => {
     expect(subgraphButton.exists()).toBe(false)
   })
 
-  it('should not show subgraph button in readonly mode', async () => {
-    await setupMocks(true) // isSubgraph = true
-
-    const wrapper = createWrapper({
-      nodeData: createMockNodeData('test-node-1'),
-      readonly: true
-    })
-
-    await wrapper.vm.$nextTick()
-
-    const subgraphButton = wrapper.find('[data-testid="subgraph-enter-button"]')
-    expect(subgraphButton.exists()).toBe(false)
-  })
-
   it('should emit enter-subgraph event when button is clicked', async () => {
     await setupMocks(true) // isSubgraph = true