BUG: mj-image flickers / reloads on every non-src attribute or style edit

### GrapesJS version

- [x] I confirm to use the latest version of GrapesJS

### GrapesJS MJML version

- [x] I confirm to use the latest version of GrapesJS MJML

### What browser are you using?

Chrome (latest) — the root cause is at the DOM level, so it isn't browser-specific.

### Reproducible demo link

https://stackblitz.com/github/geonsang-jo/grapesjs-mjml-image-reconcile-demo/tree/fix/canvas-height-and-visible-flicker?file=src%2Fmain.ts&startScript=dev&view=preview

### Describe the bug

**How to reproduce the bug?**
1. Add an `mj-image` to the canvas.
2. Edit any of its **non-`src`** attributes or styles — `alt`, `title`, `padding`, `width`, alignment — in the Trait/Style Manager.
3. Watch the rendered image.

The StackBlitz demo above is a side-by-side **Baseline vs. Patched** repro (use *Toggle width once* / *Start auto toggle*); the page reports whether the rendered `` DOM object was replaced.

**What is the expected behavior?**
Editing a non-`src` attribute or style updates the image in place; the already-loaded image stays visible and does not reload.

**What is the current behavior?**
The `` visibly flickers on every edit — it briefly disappears, then reloads and repaints.

Root cause: the MJML view re-renders a component by rebuilding its entire subtree on every `change:attributes` / `change:src` event:

```js
// src/components/index.ts — coreMjmlView.render()
this.el.innerHTML = this.getTemplateFromMjml();
```

Because the whole subtree is replaced, the existing `` node is destroyed and recreated each time, so the browser drops the decoded image and refetches and repaints it — even when `src` did not change.

Confirmed on `grapesjs-mjml@1.0.8`.

> I searched the existing issues: the closest are #385 (wrapper losing its children on a property edit) and #389 (redo not restoring an image), which share the same "an edit triggers a destructive full re-render" mechanism, but neither reports the `mj-image` flicker/reload specifically. I have an `mj-image`-scoped DOM-reconciliation fix ready and will open a PR.

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct