fix: dragging (e.g., when selecting text) in Markdown note causes node to drag (#8413)

## Summary

When attempting to select text inside Vue node Markdown widget's
textarea (edit mode), the node would drag instead of text being
selected.

Root cause: WidgetMarkdown.vue's Textarea only had @click.stop and
@keydown.stop, but was missing pointer event modifiers. The pointerdown
event bubbled up to LGraphNode.vue which initiated node drag.

*Fix*: Add @pointerdown.capture.stop, @pointermove.capture.stop, and
@pointerup.capture.stop to match the pattern used in WidgetTextarea.vue.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8413-fix-dragging-e-g-when-selecting-text-in-Markdown-note-causes-node-to-drag-2f76d73d3650816dbf9bdf893775c3d4)
by [Unito](https://www.unito.io)

Co-authored-by: Subagent 5 <subagent@example.com>
Co-authored-by: Amp <amp@ampcode.com>

src/renderer/extensions/vueNodes/widgets/components/WidgetMarkdown.test.ts

@@ -206,6 +206,60 @@ describe('WidgetMarkdown Dual Mode Display', () => {
       expect(clickSpy).not.toHaveBeenCalled()
       expect(keydownSpy).not.toHaveBeenCalled()
     })
+
+    describe('Pointer Event Propagation', () => {
+      it('stops pointerdown propagation to prevent node drag during text selection', async () => {
+        const widget = createMockWidget('# Test')
+        const wrapper = mountComponent(widget, '# Test')
+
+        await clickToEdit(wrapper)
+
+        const textarea = wrapper.find('textarea')
+        expect(textarea.exists()).toBe(true)
+
+        const parentPointerdownHandler = vi.fn()
+        const wrapperEl = wrapper.element as HTMLElement
+        wrapperEl.addEventListener('pointerdown', parentPointerdownHandler)
+
+        await textarea.trigger('pointerdown')
+
+        expect(parentPointerdownHandler).not.toHaveBeenCalled()
+      })
+
+      it('stops pointermove propagation during text selection', async () => {
+        const widget = createMockWidget('# Test')
+        const wrapper = mountComponent(widget, '# Test')
+
+        await clickToEdit(wrapper)
+
+        const textarea = wrapper.find('textarea')
+
+        const parentPointermoveHandler = vi.fn()
+        const wrapperEl = wrapper.element as HTMLElement
+        wrapperEl.addEventListener('pointermove', parentPointermoveHandler)
+
+        await textarea.trigger('pointermove')
+
+        expect(parentPointermoveHandler).not.toHaveBeenCalled()
+      })
+
+      it('stops pointerup propagation after text selection', async () => {
+        const widget = createMockWidget('# Test')
+        const wrapper = mountComponent(widget, '# Test')
+
+        await clickToEdit(wrapper)
+
+        const textarea = wrapper.find('textarea')
+
+        const parentPointerupHandler = vi.fn()
+        const wrapperEl = wrapper.element as HTMLElement
+        wrapperEl.addEventListener('pointerup', parentPointerupHandler)
+
+        await textarea.trigger('pointerup')
+
+        expect(parentPointerupHandler).not.toHaveBeenCalled()
+      })
+    })
   })
 
   describe('Value Updates', () => {

src/renderer/extensions/vueNodes/widgets/components/WidgetMarkdown.vue

@@ -21,6 +21,9 @@
         }
       }"
       data-capture-wheel="true"
+      @pointerdown.capture.stop
+      @pointermove.capture.stop
+      @pointerup.capture.stop
       @click.stop
       @keydown.stop
     />