feat: add cloud gtm injection (#8311)

## Summary

Add GTM injection for cloud distribution builds and push SPA page view +
signup events.

## Changes

- **What**: Inject GTM script into head-prepend and noscript iframe into
body-prepend for cloud builds
- **What**: Push `page_view` to `dataLayer` on cloud route changes
(page_location + page_title)
- **What**: Push `sign_up` to `dataLayer` after successful account
creation (email/google/github)
- **Dependencies**: None

## Review Focus

- Placement order for head-prepend/body-prepend and cloud-only gating
- Route-change page_view payload shape
- Signup event emission only for new users

## Screenshots (if applicable)

<img width="1512" height="860" alt="Screenshot 2026-01-26 at 11 38
11 AM"
src="https://github.com/user-attachments/assets/03fb61db-5ca4-4432-9704-bbdcc4c6c1b7"
/>

<img width="1512" height="862" alt="Screenshot 2026-01-26 at 11 38
26 AM"
src="https://github.com/user-attachments/assets/6e46c855-a552-4e52-9800-17898a512d4d"
/>

src/stores/firebaseAuthStore.ts

@@ -26,6 +26,7 @@ import { t } from '@/i18n'
 import { WORKSPACE_STORAGE_KEYS } from '@/platform/auth/workspace/workspaceConstants'
 import { isCloud } from '@/platform/distribution/types'
 import { useTelemetry } from '@/platform/telemetry'
+import { pushDataLayerEvent as pushDataLayerEventBase } from '@/platform/telemetry/gtm'
 import { useDialogService } from '@/services/dialogService'
 import { useApiKeyAuthStore } from '@/stores/apiKeyAuthStore'
 import type { AuthHeader } from '@/types/authTypes'
@@ -81,6 +82,42 @@ export const useFirebaseAuthStore = defineStore('firebaseAuth', () => {
 
   const buildApiUrl = (path: string) => `${getComfyApiBaseUrl()}${path}`
 
+  function pushDataLayerEvent(event: Record<string, unknown>): void {
+    if (!isCloud || typeof window === 'undefined') return
+
+    try {
+      pushDataLayerEventBase(event)
+    } catch (error) {
+      console.warn('Failed to push data layer event', error)
+    }
+  }
+
+  async function hashSha256(value: string): Promise<string | undefined> {
+    if (typeof crypto === 'undefined' || !crypto.subtle) return
+    if (typeof TextEncoder === 'undefined') return
+    const data = new TextEncoder().encode(value)
+    const hash = await crypto.subtle.digest('SHA-256', data)
+    return Array.from(new Uint8Array(hash))
+      .map((b) => b.toString(16).padStart(2, '0'))
+      .join('')
+  }
+
+  async function trackSignUp(method: 'email' | 'google' | 'github') {
+    if (!isCloud || typeof window === 'undefined') return
+
+    try {
+      const userId = currentUser.value?.uid
+      const hashedUserId = userId ? await hashSha256(userId) : undefined
+      pushDataLayerEvent({
+        event: 'sign_up',
+        method,
+        ...(hashedUserId ? { user_id: hashedUserId } : {})
+      })
+    } catch (error) {
+      console.warn('Failed to track sign up', error)
+    }
+  }
+
   // Providers
   const googleProvider = new GoogleAuthProvider()
   googleProvider.addScope('email')
@@ -347,6 +384,7 @@ export const useFirebaseAuthStore = defineStore('firebaseAuth', () => {
         method: 'email',
         is_new_user: true
       })
+      await trackSignUp('email')
     }
 
     return result
@@ -365,6 +403,9 @@ export const useFirebaseAuthStore = defineStore('firebaseAuth', () => {
         method: 'google',
         is_new_user: isNewUser
       })
+      if (isNewUser) {
+        await trackSignUp('google')
+      }
     }
 
     return result
@@ -383,6 +424,9 @@ export const useFirebaseAuthStore = defineStore('firebaseAuth', () => {
         method: 'github',
         is_new_user: isNewUser
       })
+      if (isNewUser) {
+        await trackSignUp('github')
+      }
     }
 
     return result