fix: make zPreviewOutput accept text-only job outputs (#9724)

## Summary

Fixes Zod validation crash when the jobs batch contains text-only
preview outputs (e.g. from LLM nodes), which caused the entire Assets
sidebar to show nothing.

## Changes

- **What**: Made `filename`, `subfolder`, and `type` optional in
`zPreviewOutput` and added `.passthrough()` for extra fields like
`content`. Text-only jobs are safely filtered out downstream by
`supportsPreview`.
- Added tests in `fetchJobs.test.ts` verifying a mixed batch (image +
text-only + no-preview) parses successfully.
- Added test in `assetsStore.test.ts` verifying text-only jobs are
skipped without breaking sibling image jobs. Improved `TaskItemImpl`
mock to realistically handle media types.

## Review Focus

- The `zPreviewOutput` schema now uses `.passthrough()` to allow extra
fields from new preview types (like `content` on text previews). This is
consistent with `zRawJobListItem` and `zExecutionError` which also use
`.passthrough()`.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9724-fix-make-zPreviewOutput-accept-text-only-job-outputs-31f6d73d36508119a7aef99f9b765ecd)
by [Unito](https://www.unito.io)

src/platform/remote/comfyui/jobs/fetchJobs.test.ts

@@ -150,6 +150,41 @@ describe('fetchJobs', () => {
 
       expect(result).toEqual([])
     })
+
+    it('parses batch containing text-only preview outputs', async () => {
+      const mockFetch = vi.fn().mockResolvedValue({
+        ok: true,
+        json: () =>
+          Promise.resolve(
+            createMockResponse([
+              createMockJob('image-job', 'completed', {
+                preview_output: {
+                  filename: 'output.png',
+                  subfolder: '',
+                  type: 'output',
+                  nodeId: '1',
+                  mediaType: 'images'
+                }
+              }),
+              createMockJob('text-job', 'completed', {
+                preview_output: {
+                  content: 'some generated text',
+                  nodeId: '5',
+                  mediaType: 'text'
+                }
+              }),
+              createMockJob('no-preview-job', 'completed')
+            ])
+          )
+      })
+
+      const result = await fetchHistory(mockFetch)
+
+      expect(result).toHaveLength(3)
+      expect(result[0].id).toBe('image-job')
+      expect(result[1].id).toBe('text-job')
+      expect(result[2].id).toBe('no-preview-job')
+    })
   })
 
   describe('fetchQueue', () => {

src/platform/remote/comfyui/jobs/jobTypes.ts

@@ -18,14 +18,16 @@ const zJobStatus = z.enum([
   'cancelled'
 ])
 
-const zPreviewOutput = z.object({
-  filename: z.string(),
-  subfolder: z.string(),
-  type: resultItemType,
-  nodeId: z.string(),
-  mediaType: z.string(),
-  display_name: z.string().optional()
-})
+const zPreviewOutput = z
+  .object({
+    filename: z.string().optional(),
+    subfolder: z.string().optional(),
+    type: resultItemType.optional(),
+    nodeId: z.string(),
+    mediaType: z.string(),
+    display_name: z.string().optional()
+  })
+  .passthrough()
 
 /**
  * Execution error from Jobs API.