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/composables/README.md

@@ -247,7 +247,7 @@ General-purpose composables:
 | `useTreeExpansion`          | Handles tree node expansion state                         |
 
 | `useWorkflowAutoSave` | Handles automatic workflow saving |
-| `useWorkflowPersistence` | Manages workflow persistence |
+| `useWorkflowPersistenceV2` | Manages workflow persistence |
 | `useWorkflowValidation` | Validates workflow integrity |
 
 ## Usage Guidelines

src/composables/useFeatureFlags.ts

@@ -23,7 +23,10 @@ export enum ServerFeatureFlag {
   TEAM_WORKSPACES_ENABLED = 'team_workspaces_enabled',
   USER_SECRETS_ENABLED = 'user_secrets_enabled',
   NODE_REPLACEMENTS = 'node_replacements',
-  NODE_LIBRARY_ESSENTIALS_ENABLED = 'node_library_essentials_enabled'
+  NODE_LIBRARY_ESSENTIALS_ENABLED = 'node_library_essentials_enabled',
+  WORKFLOW_SHARING_ENABLED = 'workflow_sharing_enabled',
+  COMFYHUB_UPLOAD_ENABLED = 'comfyhub_upload_enabled',
+  COMFYHUB_PROFILE_GATE_ENABLED = 'comfyhub_profile_gate_enabled'
 }
 
 /**
@@ -130,6 +133,29 @@ export function useFeatureFlags() {
           false
         )
       )
+    },
+    get workflowSharingEnabled() {
+      // UI is also gated on `isCloud` in TopMenuSection; default false
+      // to match other flags' opt-in convention.
+      return resolveFlag(
+        ServerFeatureFlag.WORKFLOW_SHARING_ENABLED,
+        remoteConfig.value.workflow_sharing_enabled,
+        false
+      )
+    },
+    get comfyHubUploadEnabled() {
+      return resolveFlag(
+        ServerFeatureFlag.COMFYHUB_UPLOAD_ENABLED,
+        remoteConfig.value.comfyhub_upload_enabled,
+        false
+      )
+    },
+    get comfyHubProfileGateEnabled() {
+      return resolveFlag(
+        ServerFeatureFlag.COMFYHUB_PROFILE_GATE_ENABLED,
+        remoteConfig.value.comfyhub_profile_gate_enabled,
+        false
+      )
     }
   })