split into workspace: poc-memory and poc-daemon subcrates

poc-daemon (notification routing, idle timer, IRC, Telegram) was already
fully self-contained with no imports from the poc-memory library. Now it's
a proper separate crate with its own Cargo.toml and capnp schema.

poc-memory retains the store, graph, search, neuro, knowledge, and the
jobkit-based memory maintenance daemon (daemon.rs).

Co-Authored-By: ProofOfConcept <poc@bcachefs.org>

poc-daemon/build.rs

@@ -0,0 +1,6 @@
+fn main() {
+    capnpc::CompilerCommand::new()
+        .file("schema/daemon.capnp")
+        .run()
+        .expect("capnp compile failed");
+}