fix: clear stale progress bar on SubgraphNode after navigation (#9865)

## Problem

When navigating back from a subgraph to the root graph, the SubgraphNode
can retain a stale progress bar. This happens because the progress
watcher in `GraphCanvas.vue` watches `[nodeLocationProgressStates,
canvasStore.canvas]`, but neither value changes reference during
subgraph navigation:

- `nodeLocationProgressStates` is already `{}` (execution completed
while viewing the subgraph)
- `canvasStore.canvas` is a `shallowRef` set once at startup — only
`canvas.graph` changes (via `setGraph()`)

**Reproduction** (from PR #4382 comment thread by @guill):
1. Create a subgraph with a KSampler
2. Execute the workflow
3. While progress bar is halfway, enter the subgraph
4. Wait for execution to complete
5. Navigate back to root graph
6. Progress bar is stuck at 50%

## Root Cause

`canvasStore.canvas` is a `shallowRef` — subgraph navigation mutates
`canvas.graph` (a nested property) via `LGraphCanvas.setGraph()`, which
doesn't trigger a shallow watch. The watcher never re-fires to clear
stale `node.progress` values.

## Fix

Add `canvasStore.currentGraph` to the watcher's dependency array. This
is already a `shallowRef` in `canvasStore` that's updated on every
`litegraph:set-graph` event. Zero overhead, precise targeting.

## Context

- Original discussion:
https://github.com/Comfy-Org/ComfyUI_frontend/pull/4382/files/BASE..868e047272f6c5d710db7e607b8997d4c243490f#r2202024855
- PR #9248 correctly removed `deep: true` from this watcher but missed
the subgraph edge case
- `deep: true` was the wrong fix — `canvasStore.currentGraph` is the
precise solution

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9865-fix-clear-stale-progress-bar-on-SubgraphNode-after-navigation-3226d73d3650811c8f9de612d81ef98a)
by [Unito](https://www.unito.io)

src/components/graph/GraphCanvas.vue

@@ -381,10 +381,17 @@ watch(
  * No `deep: true` needed — `nodeLocationProgressStates` is a computed that
  * returns a new `Record` object on every progress event (the underlying
  * `nodeProgressStates` ref is replaced wholesale by the WebSocket handler).
+ *
+ * `currentGraph` triggers this watcher on subgraph navigation so stale
+ * progress bars are cleared when returning to the root graph.
  */
 watch(
   () =>
-    [executionStore.nodeLocationProgressStates, canvasStore.canvas] as const,
+    [
+      executionStore.nodeLocationProgressStates,
+      canvasStore.canvas,
+      canvasStore.currentGraph
+    ] as const,
   ([nodeLocationProgressStates, canvas]) => {
     if (!canvas?.graph) return
     for (const node of canvas.graph.nodes) {