refactor: workspaces DDD (#8921)

## Summary

Refactor: workspaces related functionality into DDD structure.

Note: this is the 1st PR of 2 more refactoring.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8921-refactor-DDD-3096d73d3650812bb7f6eb955f042663)
by [Unito](https://www.unito.io)

src/platform/workspace/auth/WorkspaceAuthGate.vue

@@ -0,0 +1,129 @@
+<template>
+  <slot v-if="isReady" />
+  <div
+    v-else
+    class="fixed inset-0 z-[1100] flex items-center justify-center bg-[var(--p-mask-background)]"
+  >
+    <ProgressSpinner />
+  </div>
+</template>
+
+<script setup lang="ts">
+/**
+ * WorkspaceAuthGate - Conditional auth checkpoint for workspace mode.
+ *
+ * This gate ensures proper initialization order for workspace-scoped auth:
+ * 1. Wait for Firebase auth to resolve
+ * 2. Check if teamWorkspacesEnabled feature flag is on
+ * 3. If YES: Initialize workspace token and store before rendering
+ * 4. If NO: Render immediately using existing Firebase auth
+ *
+ * This prevents race conditions where API calls use Firebase tokens
+ * instead of workspace tokens when the workspace feature is enabled.
+ */
+import { promiseTimeout, until } from '@vueuse/core'
+import { storeToRefs } from 'pinia'
+import ProgressSpinner from 'primevue/progressspinner'
+import { onMounted, ref } from 'vue'
+
+import { useFeatureFlags } from '@/composables/useFeatureFlags'
+import { isCloud } from '@/platform/distribution/types'
+import { refreshRemoteConfig } from '@/platform/remoteConfig/refreshRemoteConfig'
+import { useTeamWorkspaceStore } from '@/platform/workspace/stores/teamWorkspaceStore'
+import { useFirebaseAuthStore } from '@/stores/firebaseAuthStore'
+
+const FIREBASE_INIT_TIMEOUT_MS = 16_000
+const CONFIG_REFRESH_TIMEOUT_MS = 10_000
+
+const isReady = ref(!isCloud)
+
+async function initialize(): Promise<void> {
+  if (!isCloud) return
+
+  const authStore = useFirebaseAuthStore()
+  const { isInitialized, currentUser } = storeToRefs(authStore)
+
+  try {
+    // Step 1: Wait for Firebase auth to resolve
+    // This is shared with router guard - both wait for the same thing,
+    // but this gate blocks rendering while router guard blocks navigation
+    if (!isInitialized.value) {
+      await until(isInitialized).toBe(true, {
+        timeout: FIREBASE_INIT_TIMEOUT_MS
+      })
+    }
+
+    // Step 2: If not authenticated, nothing more to do
+    // Unauthenticated users don't have workspace context
+    if (!currentUser.value) {
+      isReady.value = true
+      return
+    }
+
+    // Step 3: Refresh feature flags with auth context
+    // This ensures teamWorkspacesEnabled reflects the authenticated user's state
+    // Timeout prevents hanging if server is slow/unresponsive
+    try {
+      await Promise.race([
+        refreshRemoteConfig({ useAuth: true }),
+        promiseTimeout(CONFIG_REFRESH_TIMEOUT_MS).then(() => {
+          throw new Error('Config refresh timeout')
+        })
+      ])
+    } catch (error) {
+      console.warn(
+        '[WorkspaceAuthGate] Failed to refresh remote config:',
+        error
+      )
+      // Continue - feature flags will use defaults (teamWorkspacesEnabled=false)
+      // App will render with Firebase auth fallback
+    }
+
+    // Step 4: THE CHECKPOINT - Are we in workspace mode?
+    const { flags } = useFeatureFlags()
+    if (!flags.teamWorkspacesEnabled) {
+      // Not in workspace mode - use existing Firebase auth flow
+      // No additional initialization needed
+      isReady.value = true
+      return
+    }
+
+    // Step 5: WORKSPACE MODE - Full initialization
+    await initializeWorkspaceMode()
+  } catch (error) {
+    console.error('[WorkspaceAuthGate] Initialization failed:', error)
+  } finally {
+    // Always render (graceful degradation)
+    // If workspace init failed, API calls fall back to Firebase token
+    isReady.value = true
+  }
+}
+
+async function initializeWorkspaceMode(): Promise<void> {
+  // Initialize the full workspace store which handles:
+  // - Restoring workspace token from session (fast path for refresh)
+  // - Fetching workspace list
+  // - Switching to last used workspace if needed
+  // - Setting active workspace
+  try {
+    const workspaceStore = useTeamWorkspaceStore()
+    if (workspaceStore.initState === 'uninitialized') {
+      await workspaceStore.initialize()
+    }
+  } catch (error) {
+    // Log but don't block - workspace UI features may not work but app will render
+    // API calls will fall back to Firebase token
+    console.warn(
+      '[WorkspaceAuthGate] Failed to initialize workspace store:',
+      error
+    )
+  }
+}
+
+// Initialize on mount. This gate should be placed on the authenticated layout
+// (LayoutDefault) so it mounts fresh after login and unmounts on logout.
+// The router guard ensures only authenticated users reach this layout.
+onMounted(() => {
+  void initialize()
+})
+</script>