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/components/chat/message/parts/ReasoningPart.tsx

@@ -1,6 +1,6 @@
 import React from 'react';
 import type { ComponentType } from 'react';
-import type { Part } from '@opencode-ai/sdk';
+import type { Part } from '@opencode-ai/sdk/v2';
 import { RiArrowDownSLine, RiArrowRightSLine, RiBrainAi3Line, RiChatAi3Line } from '@remixicon/react';
 import { cn } from '@/lib/utils';
 import type { ContentChangeReason } from '@/hooks/useChatScrollManager';