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/stores/useConfigStore.ts

@@ -1,7 +1,7 @@
 import { create } from "zustand";
 import type { StoreApi, UseBoundStore } from "zustand";
 import { devtools, persist, createJSONStorage } from "zustand/middleware";
-import type { Provider, Agent } from "@opencode-ai/sdk";
+import type { Provider, Agent } from "@opencode-ai/sdk/v2";
 import { opencodeClient } from "@/lib/opencode/client";
 import { scopeMatches, subscribeToConfigChanges } from "@/lib/configSync";
 import type { ModelMetadata } from "@/types";