feat: migrate to OpenCode SDK v2

Update all import statements to use @opencode-ai/sdk/v2
Modify Vite configurations to alias new SDK path
Update API client method signatures for SDK v2 compatibility

packages/ui/src/hooks/useModelLists.ts

@@ -1,7 +1,7 @@
 import React from 'react';
 import { useConfigStore } from '@/stores/useConfigStore';
 import { useUIStore } from '@/stores/useUIStore';
-import type { Provider } from '@opencode-ai/sdk';
+import type { Provider } from '@opencode-ai/sdk/v2';
 
 type ProviderModel = Provider["models"][string];
 type ProviderWithModelList = Omit<Provider, "models"> & { models: ProviderModel[] };