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/platform/workflow/validation/schemas/workflowSchema.ts

@@ -553,7 +553,6 @@ export type ComfyApiWorkflow = z.infer<typeof zComfyApiWorkflow>
  * where that definition is instantiated in the workflow.
  *
  * "def-A" → ["5", "10"] for each container node instantiating that subgraph definition.
- * @knipIgnoreUsedByStackedPR
  */
 export function buildSubgraphExecutionPaths(
   rootNodes: ComfyNode[],