Wire InfoCommand through as one real, runnable example

BambuRequest::Info(InfoCommand) is now live (was commented out) —
examples/bambu_protocol_demo.rs constructs one, serializes it, and prints
it next to Bambu's real wire JSON for comparison. Run it and copy this
exact shape (proto message -> use it here -> add an enum variant) for
every other command.

examples/bambu_protocol_demo.rs

@@ -0,0 +1,24 @@
+//! Run with: cargo run --example bambu_protocol_demo
+//!
+//! Proves the whole pipeline end to end: a message written in
+//! continuum-schemas' proto/bambulab/v1/request.proto, compiled by prost
+//! into a real Rust struct, wrapped in the hand-written BambuRequest enum,
+//! and serialized by plain serde — no protobuf binary encoding involved,
+//! since Bambu's actual wire format is JSON over MQTT.
+
+use continuum_proxy::printer::BambuRequest;
+use continuum_types::bambulab::v1::InfoCommand;
+
+fn main() {
+    let request = BambuRequest::Info(InfoCommand {
+        sequence_id: "0".to_string(),
+        command: "get_version".to_string(),
+    });
+
+    let actual = serde_json::to_string(&request).unwrap();
+    let expected = r#"{"info":{"sequence_id":"0","command":"get_version"}}"#;
+
+    println!("generated: {actual}");
+    println!("Bambu's real wire format: {expected}");
+    println!("match: {}", actual == expected);
+}