fix(client): address PR #65 review — POI key, ToldBy parsing, KG dirty flag

- minimap.gd: fix "poi_category" → "category" key mismatch so POI
  colors and shapes render correctly
- journal_panel.gd: parse ToldBy(N) source format, resolve entity
  names from player_knowledge; move confidence/source labels to
  UIStrings per D-042
- observer/mod.rs: add Changed<KnowledgeGraph> dirty flag to skip
  per-tick KG serialization when unchanged
- types.rs: fix stale version doc comment (13 → 14)

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

server/src/perception/observer/mod.rs

@@ -72,7 +72,7 @@ pub fn compute_observer_snapshot(
             Entity,
             &TilePosition,
             Option<&Facing>,
-            &KnowledgeGraph,
+            Ref<KnowledgeGraph>,
             &mut NearbyInteractionBuffer,
             &mut MonologueBuffer,
             Option<&Stance>,
@@ -120,6 +120,10 @@ pub fn compute_observer_snapshot(
         return;
     };
 
+    // D-041 dirty flag: only re-serialize KG dump when observer's graph changed this tick.
+    let kg_changed = observer_kg.is_changed();
+    let observer_kg: &KnowledgeGraph = &observer_kg;
+
     let facing = facing_opt
         .map(|f| f.0)
         .unwrap_or(FacingDirection::default());
@@ -290,8 +294,10 @@ pub fn compute_observer_snapshot(
         .collect();
 
     // Build player knowledge dump for journal panel (#264, D-041).
-    // Sends full KG state — client-side filtering for display grouping.
-    let player_knowledge = {
+    // Only re-serialize when the observer's KG was mutated this tick (Changed filter).
+    // When unchanged, player_knowledge = None → field omitted from wire (skip_serializing_if).
+    // Client keeps its last value (apply_snapshot only updates when field is present).
+    let player_knowledge = if kg_changed {
         let kg_entities: Vec<KnownEntityWire> = observer_kg
             .known_entities_iter()
             .map(|(sid, ek)| {
@@ -363,6 +369,8 @@ pub fn compute_observer_snapshot(
                 facts: kg_facts,
             })
         }
+    } else {
+        None
     };
 
     buffer.snapshot = Some(ObserverSnapshot {