fix(ci): remove duplicate doc comment, add rng_seed serialization tests (#344, #527)

Review fixes: deduplicate dump_schedule_graph doc comment,
add rng_seed round-trip test and v9→v10 backward compat test.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/main.rs

@@ -184,9 +184,6 @@ fn main() {
     tracing::info!("Simulation server shutting down");
 }
 
-/// Print bevy_ecs schedule graph and exit.
-/// Invoked by --dump-schedule CLI flag (#346).
-///
 /// Print bevy_ecs schedule graph and exit.
 /// Invoked by --dump-schedule CLI flag (#346).
 ///