fix(simulation): address PR #42 review — 8 items from Hoshe and Tyre

1. Sound producers: document empty v0.1 pipeline explicitly (critical)
2. Routine tests: add ActiveSim to 3 tests that passed trivially
3. Rename _observer_pos → observer_pos (used at line 191)
4. Add FactionOnly positive test case (matching faction_id)
5. Fix stale doc comment "Current: 9" → 10 in ObserverSnapshot
6. Remove orphaned SimulationTier/LastInteraction/ScopeTag types
7. Add tracing::warn on FactionOnly non-numeric parse failure
8. Document Medium-range occlusion gap as TODO in audible_at
9. Insert SoundEventQueue in observer test setup_world

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

server/src/simulation/tier.rs

@@ -4,8 +4,6 @@
 
 use bevy_app::prelude::*;
 use bevy_ecs::prelude::*;
-use serde::{Deserialize, Serialize};
-
 use crate::simulation::movement::{PlayerCharacter, TilePosition};
 
 // --- Tier radius constants (D-026) ---
@@ -131,68 +129,11 @@ pub fn update_tier_markers(
     }
 }
 
-#[derive(Component, Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
-pub enum SimulationTier {
-    Active,
-    Background,
-    StateSaved,
-    Ungenerated,
-}
-
-#[derive(Component, Debug, Clone)]
-pub struct LastInteraction {
-    pub tick: u64,
-}
-
-#[derive(Component, Debug, Clone)]
-pub struct ScopeTag {
-    pub tags: Vec<ScopeKind>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
-pub enum ScopeKind {
-    Neighborhood,
-    ActiveQuest,
-    Colleague,
-    KnownContact,
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
     use bevy_ecs::world::World;
 
-    // --- SimulationTier enum tests ---
-
-    #[test]
-    fn tier_can_be_added_and_queried() {
-        let mut world = World::new();
-        let entity = world.spawn(SimulationTier::Active).id();
-        assert_eq!(
-            *world.get::<SimulationTier>(entity).unwrap(),
-            SimulationTier::Active
-        );
-    }
-
-    #[test]
-    fn tier_can_transition() {
-        let mut world = World::new();
-        let entity = world.spawn(SimulationTier::Active).id();
-        world.entity_mut(entity).insert(SimulationTier::Background);
-        assert_eq!(
-            *world.get::<SimulationTier>(entity).unwrap(),
-            SimulationTier::Background
-        );
-    }
-
-    #[test]
-    fn all_tier_variants_are_distinct() {
-        assert_ne!(SimulationTier::Active, SimulationTier::Background);
-        assert_ne!(SimulationTier::Background, SimulationTier::StateSaved);
-        assert_ne!(SimulationTier::StateSaved, SimulationTier::Ungenerated);
-        assert_ne!(SimulationTier::Active, SimulationTier::Ungenerated);
-    }
-
     // --- Marker component query correctness (D-026, #94) ---
     // These tests verify that With<ActiveSim> / With<BackgroundSim> / With<StateSaved>
     // filter correctly — the core guarantee that behavior systems only run for the
@@ -338,57 +279,6 @@ mod tests {
         assert!(world.get::<ActiveSim>(entity).is_none());
     }
 
-    // --- LastInteraction and ScopeTag ---
-
-    #[test]
-    fn last_interaction_records_tick() {
-        let mut world = World::new();
-        let entity = world.spawn(LastInteraction { tick: 42 }).id();
-
-        let interaction = world.get::<LastInteraction>(entity).unwrap();
-        assert_eq!(interaction.tick, 42);
-    }
-
-    #[test]
-    fn last_interaction_tick_can_be_updated() {
-        let mut world = World::new();
-        let entity = world.spawn(LastInteraction { tick: 1 }).id();
-
-        world.entity_mut(entity).insert(LastInteraction { tick: 100 });
-
-        let interaction = world.get::<LastInteraction>(entity).unwrap();
-        assert_eq!(interaction.tick, 100);
-    }
-
-    #[test]
-    fn scope_tag_neighborhood_kind() {
-        let mut world = World::new();
-        let entity = world
-            .spawn(ScopeTag {
-                tags: vec![ScopeKind::Neighborhood],
-            })
-            .id();
-
-        let tag = world.get::<ScopeTag>(entity).unwrap();
-        assert!(tag.tags.contains(&ScopeKind::Neighborhood));
-        assert!(!tag.tags.contains(&ScopeKind::ActiveQuest));
-    }
-
-    #[test]
-    fn scope_tag_multiple_kinds() {
-        let entity = ScopeTag {
-            tags: vec![
-                ScopeKind::Neighborhood,
-                ScopeKind::Colleague,
-                ScopeKind::KnownContact,
-            ],
-        };
-        assert_eq!(entity.tags.len(), 3);
-        assert!(entity.tags.contains(&ScopeKind::Colleague));
-        assert!(entity.tags.contains(&ScopeKind::KnownContact));
-        assert!(!entity.tags.contains(&ScopeKind::ActiveQuest));
-    }
-
     // --- TierPlugin smoke test ---
 
     #[test]