feat(lsp): add background daemon for language servers

daemon.ts

@@ -0,0 +1,11 @@
+#!/usr/bin/env -S npx tsx
+// Daemon Entrypoint - Spawned (detached) by ensureDaemon() in
+// src/daemonProtocol.ts the first time any client tries to connect.
+// Stays alive across CLI invocations; idle LSP servers within are reaped
+// per ServerConfig.idleTtlMs.
+import { startDaemon } from "./src/daemon.ts";
+
+startDaemon().catch((err) => {
+  process.stderr.write(`pi-lsp daemon failed to start: ${err?.stack ?? err}\n`);
+  process.exit(1);
+});