[feat] Surface missing models in Errors tab (Cloud) (#9743)

## Summary
When a workflow is loaded with missing models, users currently have no
way to identify or resolve them from within the UI. This PR adds a full
missing-model detection and resolution pipeline that surfaces missing
models in the Errors tab, allowing users to install or import them
without leaving the editor.

## Changes

### Missing Model Detection
- Scan all COMBO widgets across root graph and subgraphs for model-like
filenames during workflow load
- Enrich candidates with embedded workflow metadata (url, hash,
directory) when available
- Verify asset-supported candidates against the asset store
asynchronously to confirm installation status
- Propagate missing model state to `executionErrorStore` alongside
existing node/prompt errors

### Errors Tab UI — Model Resolution
- Group missing models by directory (e.g. `checkpoints`, `loras`, `vae`)
with collapsible category cards
- Each model row displays:
  - Model name with copy-to-clipboard button
  - Expandable list of referencing nodes with locate-on-canvas button
- **Library selector**: Pick an alternative from the user's existing
models to substitute the missing model with one click
- **URL import**: Paste a Civitai or HuggingFace URL to import a model
directly; debounced metadata fetch shows filename and file size before
confirming; type-mismatch warnings (e.g. importing a LoRA into
checkpoints directory) are surfaced with an "Import Anyway" option
- **Upgrade prompt**: In cloud environment, free-tier subscribers are
shown an upgrade modal when attempting URL import
- Separate "Import Not Supported" section for custom-node models that
cannot be auto-resolved
- Status card with live download progress, completion, failure, and
category-mismatch states

### Canvas Integration
- Highlight nodes and widgets that reference missing models with error
indicators
- Propagate missing-model badges through subgraph containers so issues
are visible at every graph level

### Code Cleanup
- Simplify `surfacePendingWarnings` in workflowService, remove stale
widget-detected model merging logic
- Add `flattenWorkflowNodes` utility to workflowSchema for traversing
nested subgraph structures
- Extract `MissingModelUrlInput`, `MissingModelLibrarySelect`,
`MissingModelStatusCard` as focused single-responsibility components

## Testing
- Unit tests for scan pipeline (`missingModelScan.test.ts`): enrichment,
skip-installed, subgraph flattening
- Unit tests for store (`missingModelStore.test.ts`): state management,
removal helpers
- Unit tests for interactions (`useMissingModelInteractions.test.ts`):
combo select, URL input, import flow, library confirm
- Component tests for `MissingModelCard` and error grouping
(`useErrorGroups.test.ts`)
- Updated `workflowService.test.ts` and `workflowSchema.test.ts` for new
logic

## Review Focus
- Missing model scan + enrichment pipeline in `missingModelScan.ts`
- Interaction composable `useMissingModelInteractions.ts` — URL metadata
fetch, library install, upload fallback
- Store integration and canvas-level error propagation

## Screenshots 


https://github.com/user-attachments/assets/339a6d5b-93a3-43cd-98dd-0fb00681b66f



┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9743-feat-Surface-missing-models-in-Errors-tab-Cloud-3206d73d365081678326d3a16c2165d8)
by [Unito](https://www.unito.io)

src/renderer/extensions/vueNodes/components/LGraphNode.vue

@@ -289,6 +289,7 @@ import { useNodePreviewState } from '@/renderer/extensions/vueNodes/preview/useN
 import { nonWidgetedInputs } from '@/renderer/extensions/vueNodes/utils/nodeDataUtils'
 import { applyLightThemeColor } from '@/renderer/extensions/vueNodes/utils/nodeStyleUtils'
 import { app } from '@/scripts/app'
+import { useMissingModelStore } from '@/platform/missingModel/missingModelStore'
 import { useExecutionErrorStore } from '@/stores/executionErrorStore'
 import { useNodeOutputStore } from '@/stores/nodeOutputStore'
 import { useRightSidePanelStore } from '@/stores/workspace/rightSidePanelStore'
@@ -339,6 +340,7 @@ const isSelected = computed(() => {
 const nodeLocatorId = computed(() => getLocatorIdFromNodeData(nodeData))
 const { executing, progress } = useNodeExecutionState(nodeLocatorId)
 const executionErrorStore = useExecutionErrorStore()
+const missingModelStore = useMissingModelStore()
 const hasExecutionError = computed(
   () => executionErrorStore.lastExecutionErrorNodeId === nodeData.id
 )
@@ -349,9 +351,11 @@ const hasAnyError = computed((): boolean => {
     nodeData.hasErrors ||
     error ||
     executionErrorStore.getNodeErrors(nodeLocatorId.value) ||
+    missingModelStore.hasMissingModelOnNode(nodeLocatorId.value) ||
     (lgraphNode.value &&
       (executionErrorStore.isContainerWithInternalError(lgraphNode.value) ||
-        executionErrorStore.isContainerWithMissingNode(lgraphNode.value)))
+        executionErrorStore.isContainerWithMissingNode(lgraphNode.value) ||
+        missingModelStore.isContainerWithMissingModel(lgraphNode.value)))
   )
 })
 

src/renderer/extensions/vueNodes/components/NodeWidgets.vue

@@ -115,6 +115,7 @@ import {
   useWidgetValueStore
 } from '@/stores/widgetValueStore'
 import { usePromotionStore } from '@/stores/promotionStore'
+import { useMissingModelStore } from '@/platform/missingModel/missingModelStore'
 import { useExecutionErrorStore } from '@/stores/executionErrorStore'
 import type { SimplifiedWidget, WidgetValue } from '@/types/simplifiedWidget'
 import { cn } from '@/utils/tailwindUtil'
@@ -134,6 +135,7 @@ const canvasStore = useCanvasStore()
 const { bringNodeToFront } = useNodeZIndex()
 const promotionStore = usePromotionStore()
 const executionErrorStore = useExecutionErrorStore()
+const missingModelStore = useMissingModelStore()
 
 function handleWidgetPointerEvent(event: PointerEvent) {
   if (shouldHandleNodePointerEvents.value) return
@@ -202,6 +204,7 @@ const processedWidgets = computed((): ProcessedWidget[] => {
   const graphId = canvasStore.canvas?.graph?.rootGraph.id
 
   const nodeId = nodeData.id
+  const nodeIdStr = String(nodeId)
   const { widgets } = nodeData
   const result: ProcessedWidget[] = []
 
@@ -284,9 +287,11 @@ const processedWidgets = computed((): ProcessedWidget[] => {
       handleContextMenu,
       hasLayoutSize: widget.hasLayoutSize ?? false,
       hasError:
-        nodeErrors?.errors?.some(
+        (nodeErrors?.errors?.some(
           (error) => error.extra_info?.input_name === widget.name
-        ) ?? false,
+        ) ??
+          false) ||
+        missingModelStore.isWidgetMissingModel(nodeIdStr, widget.name),
       hidden: widget.options?.hidden ?? false,
       id: String(bareWidgetId),
       name: widget.name,