feat: workflow sharing and ComfyHub publish flow (#8951)

## Summary

Add workflow sharing by URL and a multi-step ComfyHub publish wizard,
gated by feature flags and an optional profile gate.

## Changes

- **What**: Share dialog with URL generation and asset warnings;
ComfyHub publish wizard (Describe → Examples → Finish) with thumbnail
upload and tags; profile gate flow; shared workflow URL loader with
confirmation dialog
- **Dependencies**: None (new `sharing/` module under
`src/platform/workflow/`)

## Review Focus

- Three new feature flags: `workflow_sharing_enabled`,
`comfyhub_upload_enabled`, `comfyhub_profile_gate_enabled`
- Share service API contract and stale-share detection
(`workflowShareService.ts`)
- Publish wizard and profile gate state management
- Shared workflow URL loading and query-param preservation

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8951-feat-share-workflow-by-URL-30b6d73d3650813ebbfafdad775bfb33)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: github-actions <github-actions@github.com>
Co-authored-by: GitHub Action <action@github.com>

src/stores/userFileStore.ts

@@ -8,6 +8,19 @@ import { getPathDetails } from '@/utils/formatUtil'
 import { syncEntities } from '@/utils/syncUtil'
 import { buildTree } from '@/utils/treeUtil'
 
+/**
+ * Normalizes a timestamp value that may be either a number (milliseconds)
+ * or an ISO 8601 string (from Go's time.Time JSON serialization) into
+ * a consistent millisecond timestamp.
+ */
+function normalizeTimestamp(value: number | string): number {
+  if (typeof value === 'string') {
+    const ms = new Date(value).getTime()
+    return Number.isNaN(ms) ? Date.now() : ms
+  }
+  return value
+}
+
 /**
  * Represents a file in the user's data directory.
  */
@@ -140,7 +153,7 @@ export class UserFile {
     // https://github.com/comfyanonymous/ComfyUI/pull/5446
     const updatedFile = (await resp.json()) as string | UserDataFullInfo
     if (typeof updatedFile === 'object') {
-      this.lastModified = updatedFile.modified
+      this.lastModified = normalizeTimestamp(updatedFile.modified)
       this.size = updatedFile.size
     }
     this.originalContent = this.content
@@ -175,7 +188,7 @@ export class UserFile {
     // https://github.com/comfyanonymous/ComfyUI/pull/5446
     const updatedFile = (await resp.json()) as string | UserDataFullInfo
     if (typeof updatedFile === 'object') {
-      this.lastModified = updatedFile.modified
+      this.lastModified = normalizeTimestamp(updatedFile.modified)
       this.size = updatedFile.size
     }
     return this