fix(simulation): address all round 3 PR review issues

- Register StorytellerPlugin in main() and dump_schedule_graph() so
  contamination system runs in production (critical, rounds 2+3)
- Add doc comment to z_bands_connected clarifying band indices vs
  absolute z-levels (D-110)
- Add TODO on hardcoded modifications: vec![] in save_to_file
- Init ContaminationActive in minimal_world() test helper
- Replace ChaCha20Rng with SimRng in fuzzy_map tests (D-010)

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

server/src/main.rs

@@ -147,6 +147,7 @@ fn main() {
         hot_reload: false,
     });
     app.add_plugins(settled_reach_server::content::ContentPlugin);
+    app.add_plugins(settled_reach_server::storyteller::StorytellerPlugin);
     app.insert_resource(BridgeResource::new(bridge));
     app.insert_resource(HandshakeState::Complete);
 
@@ -323,6 +324,7 @@ fn dump_schedule_graph() {
     app.add_plugins(settled_reach_server::knowledge::KnowledgePlugin);
     app.add_plugins(settled_reach_server::npc::NpcPlugin);
     app.add_plugins(settled_reach_server::content::ContentPlugin);
+    app.add_plugins(settled_reach_server::storyteller::StorytellerPlugin);
     app.insert_resource(settled_reach_server::simulation::rng::SimRng::new(0));
 
     // Access Schedules resource directly — schedules are populated by plugins