Add compile-time leaf declarations

Introduce a function-like leaf declaration macro, bind endpoint and TUI hosts to shared generated metadata, and move remote shell endpoint construction out of the leaf module into the examples and runtime assembly code.

unshell-leaves/src/remote_shell/tui.rs

@@ -7,14 +7,12 @@
 use std::string::String;
 use std::vec::Vec;
 
-use unshell::Leaf;
 use unshell::protocol::DataMessage;
 
 use crate::{LeafTui, TuiError};
 
 /// Stub TUI surface for the remote shell leaf.
-#[derive(Default, Leaf)]
-#[leaf(leaf_name = "remote_shell")]
+#[derive(Default)]
 pub struct RemoteShellTui {
     transcript: Vec<u8>,
 }