refactor(agents): split tools + PI subscribe

src/agents/pi-tools.types.ts

@@ -0,0 +1,4 @@
+import type { AgentTool } from "@mariozechner/pi-agent-core";
+
+// biome-ignore lint/suspicious/noExplicitAny: TypeBox schema type from pi-agent-core uses a different module instance.
+export type AnyAgentTool = AgentTool<any, unknown>;