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/platform/auth/session/useSessionCookie.ts

@@ -0,0 +1,65 @@
+import { api } from '@/scripts/api'
+import { isCloud } from '@/platform/distribution/types'
+import { useFirebaseAuthStore } from '@/stores/firebaseAuthStore'
+
+/**
+ * Session cookie management for cloud authentication.
+ * Creates and deletes session cookies on the ComfyUI server.
+ */
+export const useSessionCookie = () => {
+  /**
+   * Creates or refreshes the session cookie.
+   * Called after login and on token refresh.
+   */
+  const createSession = async (): Promise<void> => {
+    if (!isCloud) return
+
+    const authStore = useFirebaseAuthStore()
+    const authHeader = await authStore.getAuthHeader()
+
+    if (!authHeader) {
+      throw new Error('No auth header available for session creation')
+    }
+
+    const response = await fetch(api.apiURL('/auth/session'), {
+      method: 'POST',
+      credentials: 'include',
+      headers: {
+        ...authHeader,
+        'Content-Type': 'application/json'
+      }
+    })
+
+    if (!response.ok) {
+      const errorData = await response.json().catch(() => ({}))
+      throw new Error(
+        `Failed to create session: ${errorData.message || response.statusText}`
+      )
+    }
+  }
+
+  /**
+   * Deletes the session cookie.
+   * Called on logout.
+   */
+  const deleteSession = async (): Promise<void> => {
+    if (!isCloud) return
+
+    const response = await fetch(api.apiURL('/auth/session'), {
+      method: 'DELETE',
+      credentials: 'include'
+    })
+
+    if (!response.ok) {
+      const errorData = await response.json().catch(() => ({}))
+      throw new Error(
+        `Failed to delete session: ${errorData.message || response.statusText}`
+      )
+    }
+  }
+
+  return {
+    createSession,
+    deleteSession
+  }
+}