fix: remove remaining Sora references from frontend

The previous Sora removal missed several frontend references, causing
TypeScript build errors for sora_client_enabled and a missing SoraView.vue
import. Clean up all remaining Sora code from types, router, sidebar,
settings, store, and accounts API.

frontend/src/api/admin/accounts.ts

@@ -568,28 +568,6 @@ export async function refreshOpenAIToken(
   return data
 }
 
-/**
- * Validate Sora session token and exchange to access token
- * @param sessionToken - Sora session token
- * @param proxyId - Optional proxy ID
- * @param endpoint - API endpoint path
- * @returns Token information including access_token
- */
-export async function validateSoraSessionToken(
-  sessionToken: string,
-  proxyId?: number | null,
-  endpoint: string = '/admin/sora/st2at'
-): Promise<Record<string, unknown>> {
-  const payload: { session_token: string; proxy_id?: number } = {
-    session_token: sessionToken
-  }
-  if (proxyId) {
-    payload.proxy_id = proxyId
-  }
-  const { data } = await apiClient.post<Record<string, unknown>>(endpoint, payload)
-  return data
-}
-
 /**
  * Batch operation result type
  */
@@ -663,7 +641,6 @@ export const accountsAPI = {
   generateAuthUrl,
   exchangeCode,
   refreshOpenAIToken,
-  validateSoraSessionToken,
   batchCreate,
   batchUpdateCredentials,
   bulkUpdate,