feat: node-specific error tab with selection-aware grouping and error overlay (#8956)

## Summary
Enhances the error panel with node-specific views: single-node selection
shows errors grouped by message in compact mode, container nodes
(subgraph/group) expose child errors via a badge and "See Error" button,
and a floating ErrorOverlay appears after execution failure with a
deduplicated summary and quick navigation to the errors tab.

## Changes
- **Consolidate error tab**: Remove `TabError.vue`; merge all error
display into `TabErrors.vue` and drop the separate `error` tab type from
`rightSidePanelStore`
- **Selection-aware grouping**: Single-node selection regroups errors by
message (not `class_type`) and renders `ErrorNodeCard` in compact mode
- **Container node support**: Detect child-node errors in subgraph/group
nodes via execution ID prefix matching; show error badge and "See Error"
button in `SectionWidgets`
- **ErrorOverlay**: New floating card shown after execution failure with
deduplicated error messages, "Dismiss" and "See Errors" actions;
`isErrorOverlayOpen` / `showErrorOverlay` / `dismissErrorOverlay` added
to `executionStore`
- **Refactor**: Centralize error ID collection in `executionStore`
(`allErrorExecutionIds`, `hasInternalErrorForNode`); split `errorGroups`
into `allErrorGroups` (unfiltered) and `tabErrorGroups`
(selection-filtered); move `ErrorOverlay` business logic into
`useErrorGroups`

## Review Focus
- `useErrorGroups.ts`: split into `allErrorGroups` / `tabErrorGroups`
and the new `filterBySelection` parameter flow
- `executionStore.ts`: `hasInternalErrorForNode` helper and
`allErrorExecutionIds` computed
- `ErrorOverlay.vue`: integration with `executionStore` overlay state
and `useErrorGroups`

## Screenshots
<img width="853" height="461" alt="image"
src="https://github.com/user-attachments/assets/a49ab620-4209-4ae7-b547-fba13da0c633"
/>
<img width="854" height="203" alt="image"
src="https://github.com/user-attachments/assets/c119da54-cd78-4e7a-8b7a-456cfd348f1d"
/>
<img width="497" height="361" alt="image"
src="https://github.com/user-attachments/assets/74b16161-cf45-454b-ae60-24922fe36931"
/>

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Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: github-actions <github-actions@github.com>

src/stores/workspace/rightSidePanelStore.ts

@@ -4,7 +4,6 @@ import { computed, ref, watch } from 'vue'
 import { useSettingStore } from '@/platform/settings/settingStore'
 
 export type RightSidePanelTab =
-  | 'error'
   | 'parameters'
   | 'nodes'
   | 'settings'