add session cookie auth on cloud dist (#6295)

## Summary

Implemented cookie-based session authentication for cloud distribution,
replacing service worker approach with extension-based lifecycle hooks.

## Changes

- **What**: Added session cookie management via [extension
hooks](https://docs.comfy.org/comfyui/extensions) for login, token
refresh, and logout events
- **Architecture**: DDD-compliant structure with platform layer
(`src/platform/auth/session/`) and cloud-gated extension
- **New Extension Hooks**: `onAuthTokenRefreshed()` and
`onAuthUserLogout()` in [ComfyExtension
interface](src/types/comfy.ts:220-232)

```mermaid
sequenceDiagram
    participant User
    participant Firebase
    participant Extension
    participant Backend

    User->>Firebase: Login
    Firebase->>Extension: onAuthUserResolved
    Extension->>Backend: POST /auth/session (with JWT)
    Backend-->>Extension: Set-Cookie

    Firebase->>Firebase: Token Refresh
    Firebase->>Extension: onAuthTokenRefreshed
    Extension->>Backend: POST /auth/session (with new JWT)
    Backend-->>Extension: Update Cookie

    User->>Firebase: Logout
    Firebase->>Extension: onAuthUserLogout (user null)
    Extension->>Backend: DELETE /auth/session
    Backend-->>Extension: Clear Cookie
```

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6295-add-session-cookie-auth-on-cloud-dist-2986d73d365081868c56e5be1ad0d0d4)
by [Unito](https://www.unito.io)

src/extensions/core/cloudSessionCookie.ts

@@ -0,0 +1,25 @@
+import { useSessionCookie } from '@/platform/auth/session/useSessionCookie'
+import { useExtensionService } from '@/services/extensionService'
+
+/**
+ * Cloud-only extension that manages session cookies for authentication.
+ * Creates session cookie on login, refreshes it when token refreshes, and deletes on logout.
+ */
+useExtensionService().registerExtension({
+  name: 'Comfy.Cloud.SessionCookie',
+
+  onAuthUserResolved: async () => {
+    const { createSession } = useSessionCookie()
+    await createSession()
+  },
+
+  onAuthTokenRefreshed: async () => {
+    const { createSession } = useSessionCookie()
+    await createSession()
+  },
+
+  onAuthUserLogout: async () => {
+    const { deleteSession } = useSessionCookie()
+    await deleteSession()
+  }
+})

src/extensions/core/index.ts

@@ -28,6 +28,7 @@ import './widgetInputs'
 if (isCloud) {
   await import('./cloudRemoteConfig')
   await import('./cloudBadges')
+  await import('./cloudSessionCookie')
 
   if (window.__CONFIG__?.subscription_required) {
     await import('./cloudSubscription')