feat(providers): add native options and exact MCP grants (#3025)

* feat(providers): add native options and exact MCP grants

Keep provider policy in provider-owned schemas so unattended Hub runs can grant only requested tools from injected MCP servers. Preserve the native resolved sandbox policy when a workflow override is present, including configured writable roots.

* test(hub): verify real provider tool policy

* test(app): avoid pinning transient restart status

packages/app/e2e/support/helpers/rewind-flow.ts

@@ -160,7 +160,7 @@ export async function launchAgent(input: {
     model?: string;
     modeId?: string;
     featureValues?: Record<string, unknown>;
-    extra?: { codex?: { features?: { multi_agent_v2?: boolean } } };
+    providerOptions?: { features?: { multi_agent_v2?: boolean } };
   };
 }): Promise<AgentHandle> {
   execFileSync("git", ["init", "-b", "main"], { cwd: input.cwd, stdio: "ignore" });