fix(simulation): PR #66 review — dedup vision, spawn components, doc fixes

- vision.rs: deduplicate own-tile entity iteration, add same-tile test
- spawn.rs: add NpcVisionState, NpcMemory, PlayerAwareness to content-
  spawned NPCs (matching generate_npc)
- pressure.rs: update who_knows_full_scan doc to reflect actual call
  frequency, document O(N) acceptability at call site
- types.rs: fix stale protocol version comment (13→14)
- generate.rs: format!() → .to_string() (clippy)
- vision.rs: hardcoded 10 → TICKS_PER_GAME_MINUTE
- relationships.rs: fix comment "15%" → "20%" to match code
- pressure.rs: document total() floor-truncation
- save_state.rs: document NpcMemory exclusion as intentional

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

server/src/simulation/spatial.rs

@@ -21,6 +21,15 @@ pub trait SpatialIndex: Send + Sync {
     /// Return all entities at the exact `position`.
     fn entities_at(&self, position: &TilePosition) -> Vec<Entity>;
 
+    /// Return all entities within Manhattan distance `radius` of `position`,
+    /// **including** entities exactly at `position`. Single-pass alternative to
+    /// `entities_in_range` + `entities_at`.
+    fn entities_within(&self, position: &TilePosition, radius: u32) -> Vec<Entity> {
+        let mut result = self.entities_in_range(position, radius);
+        result.extend(self.entities_at(position));
+        result
+    }
+
     /// Insert or update an entity's position in the index.
     fn update(&mut self, entity: Entity, position: TilePosition);
 
@@ -78,6 +87,19 @@ impl SpatialIndex for NaiveSpatialIndex {
             .collect()
     }
 
+    fn entities_within(&self, position: &TilePosition, radius: u32) -> Vec<Entity> {
+        self.entries
+            .iter()
+            .filter(|(_, pos)| {
+                pos == position
+                    || pos
+                        .manhattan_distance(position)
+                        .is_some_and(|d| d <= radius)
+            })
+            .map(|(entity, _)| *entity)
+            .collect()
+    }
+
     fn update(&mut self, entity: Entity, position: TilePosition) {
         if let Some(entry) = self.entries.iter_mut().find(|(e, _)| *e == entity) {
             entry.1 = position;