feat: show missing node packs in Errors Tab with install support (#9213)

## Summary

Surfaces missing node pack information in the Errors Tab, grouped by
registry pack, with one-click install support via ComfyUI Manager.

## Changes

- **What**: Errors Tab now groups missing nodes by their registry pack
and shows a `MissingPackGroupRow` with pack name, node/pack counts, and
an Install button that triggers Manager installation. A
`MissingNodeCard` shows individual unresolvable nodes that have no
associated pack. `useErrorGroups` was extended to resolve missing node
types to their registry packs using the `/api/workflow/missing_nodes`
endpoint. `executionErrorStore` was refactored to track missing node
types separately from execution errors and expose them reactively.
- **Breaking**: None

## Review Focus

- `useErrorGroups.ts` — the new `resolveMissingNodePacks` logic fetches
pack metadata and maps node types to pack IDs; edge cases around partial
resolution (some nodes have a pack, some don't) produce both
`MissingPackGroupRow` and `MissingNodeCard` entries
- `executionErrorStore.ts` — the store now separates `missingNodeTypes`
state from `errors`; the deferred-warnings path in `app.ts` now calls
`setMissingNodeTypes` so the Errors Tab is populated even when a
workflow loads without executing

## Screenshots (if applicable)


https://github.com/user-attachments/assets/97f8d009-0cac-4739-8740-fd3333b5a85b


┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9213-feat-show-missing-node-packs-in-Errors-Tab-with-install-support-3126d73d36508197bc4bf8ebfd2125c8)
by [Unito](https://www.unito.io)

src/components/rightSidePanel/errors/ErrorNodeCard.vue

@@ -17,24 +17,26 @@
       >
         {{ card.nodeTitle }}
       </span>
-      <Button
-        v-if="card.isSubgraphNode"
-        variant="secondary"
-        size="sm"
-        class="rounded-lg text-sm shrink-0"
-        @click.stop="handleEnterSubgraph"
-      >
-        {{ t('rightSidePanel.enterSubgraph') }}
-      </Button>
-      <Button
-        variant="textonly"
-        size="icon-sm"
-        class="size-7 text-muted-foreground hover:text-base-foreground shrink-0"
-        :aria-label="t('rightSidePanel.locateNode')"
-        @click.stop="handleLocateNode"
-      >
-        <i class="icon-[lucide--locate] size-3.5" />
-      </Button>
+      <div class="flex items-center shrink-0">
+        <Button
+          v-if="card.isSubgraphNode"
+          variant="secondary"
+          size="sm"
+          class="rounded-lg text-sm shrink-0 h-8"
+          @click.stop="handleEnterSubgraph"
+        >
+          {{ t('rightSidePanel.enterSubgraph') }}
+        </Button>
+        <Button
+          variant="textonly"
+          size="icon-sm"
+          class="size-8 text-muted-foreground hover:text-base-foreground shrink-0"
+          :aria-label="t('rightSidePanel.locateNode')"
+          @click.stop="handleLocateNode"
+        >
+          <i class="icon-[lucide--locate] size-4" />
+        </Button>
+      </div>
     </div>
 
     <!-- Multiple Errors within one Card -->