fix(simulation): address PR #125 review — tick truncation, ordering, perf, protocol test

- Widen EventPort tick methods from u32 to u64 (prevents overflow)
- Add is_identity() guard on hot-path String allocation in modifiers
- Replace Vec::remove(0) with VecDeque::pop_front() in price history
- Add .after(tick_economy_simulation) ordering for debug commands
- Fix stale PROTOCOL_VERSION assertion (20 → 21) in serialization test
- Add D-181 Phase 2 visibility scope comment on serve_econ_state_query
- Eliminate double lookup in rebuild_signals via single-pass extraction
- Track economy seed TODO with backlog ticket reference

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/src/bridge/mod.rs

@@ -227,6 +227,7 @@ impl Plugin for BridgePlugin {
                     receive_bridge_inputs.before(crate::simulation::input::process_player_input),
                     debug::handle_debug_commands
                         .after(crate::simulation::input::process_player_input)
+                        .after(crate::simulation::economy::tick_economy_simulation)
                         .before(crate::perception::observer::compute_observer_snapshot),
                     crate::perception::observer::compute_visibility_geometry
                         .after(crate::simulation::movement::validate_movement),