fix: clear stale widget slotMetadata on link disconnect (#9885)

## Summary
Fixes text field becoming non-editable when a previously linked input is
removed from a custom node.

## Problem
When a widget's input was promoted to a slot, connected via a link, and
then the input was removed (e.g., by updating the custom node
definition), the widget retained stale `slotMetadata` with `linked:
true`. This prevented the widget from being editable.

## Solution
In `refreshNodeSlots`, removed the `if (slotInfo)` guard so
`widget.slotMetadata` is always assigned — either to valid metadata or
`undefined`. This ensures stale linked state is cleared when inputs no
longer match widgets.

## Acceptance Criteria
1. Text field remains editable after promote→connect→disconnect cycle
2. Text field returns to editable state when noodle disconnected
3. No mode switching needed to restore editability

## Testing
- Added regression test: "clears stale slotMetadata when input no longer
matches widget"
- All existing tests pass (18/18 in affected file)

---
**Note: This PR currently contains only the RED (failing test) commit
for TDD verification. The GREEN (fix) commit will be pushed after CI
confirms the test failure.**

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9885-fix-clear-stale-widget-slotMetadata-on-link-disconnect-3226d73d365081269319c027b42d9f6b)
by [Unito](https://www.unito.io)

src/composables/graph/useGraphNodeManager.test.ts

@@ -241,6 +241,32 @@ describe('Widget slotMetadata reactivity on link disconnect', () => {
 
     expect(widgetData?.slotMetadata?.linked).toBe(false)
   })
+
+  it('clears stale slotMetadata when input no longer matches widget', async () => {
+    const { graph, node } = createWidgetInputGraph()
+    const { vueNodeData } = useGraphNodeManager(graph)
+
+    const nodeData = vueNodeData.get(String(node.id))!
+    const widgetData = nodeData.widgets!.find((w) => w.name === 'prompt')!
+
+    expect(widgetData.slotMetadata?.linked).toBe(true)
+
+    node.inputs[0].name = 'other'
+    node.inputs[0].widget = { name: 'other' }
+    node.inputs[0].link = null
+
+    graph.trigger('node:slot-links:changed', {
+      nodeId: node.id,
+      slotType: NodeSlotType.INPUT,
+      slotIndex: 0,
+      connected: false,
+      linkId: 42
+    })
+
+    await nextTick()
+
+    expect(widgetData.slotMetadata).toBeUndefined()
+  })
 })
 
 describe('Subgraph output slot label reactivity', () => {

src/composables/graph/useGraphNodeManager.ts

@@ -520,8 +520,7 @@ export function useGraphNodeManager(graph: LGraph): GraphNodeManager {
 
     // Update only widgets with new slot metadata, keeping other widget data intact
     for (const widget of currentData.widgets ?? []) {
-      const slotInfo = slotMetadata.get(widget.slotName ?? widget.name)
-      if (slotInfo) widget.slotMetadata = slotInfo
+      widget.slotMetadata = slotMetadata.get(widget.slotName ?? widget.name)
     }
   }