style(simulation): cargo fmt + fix clippy warnings after economics integration

- `economy.rs`: fix empty_line_after_doc_comments (section ordering),
  use `is_multiple_of` for ECON_TICK_RATE check
- `debug.rs`, `input.rs`, `mod.rs`: rustfmt import ordering + indentation

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

server/src/simulation/mod.rs

@@ -170,8 +170,7 @@ impl Plugin for SimulationPlugin {
         // Economy simulation (#821, D-031) — loaded once at startup, no-op when DB absent.
         // Uses seed 0 for now; will be threaded through StartupMessage world seed (#TODO).
         if let Some((econ_sim, econ_state)) = economy::try_load_economy(0) {
-            app.insert_resource(econ_sim)
-                .insert_resource(econ_state);
+            app.insert_resource(econ_sim).insert_resource(econ_state);
         }
         // EconQueryBuffer: always registered so EconStateQuery PlayerActions are accepted
         // even when the economy DB is absent (queries just produce no response).