fix(client): address PR #11 review — type safety, perf, tests

Add Dictionary validation in game_state visible_tiles loop to prevent
crash on malformed data (Hoshe critical). Skip redundant modulate.a
writes (Hoshe suggestion). Add 3 tests: malformed visible_tiles,
facing rotation accuracy, v1 backward compatibility. Clarify D-033
Phase 1/Phase 2 comments.

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

client/scripts/constants.gd

@@ -7,7 +7,8 @@ const TILE_SIZE: int = 32
 
 # D-033: Entity relationship color palette
 # Color represents the player's RELATIONSHIP to the entity, not an objective property.
-# Phase 1: default colors by entity kind. Phase 2 (#361): driven by RelationshipState.
+# Phase 1: default colors mapped by entity kind (Player/Npc/Object/Terrain).
+# Phase 2 (#361): colors derived from RelationshipState via the knowledge graph.
 const ENTITY_COLOR_UNKNOWN: Color = Color("#4a9ebb")   # Unknown/Neutral — cool teal
 const ENTITY_COLOR_FRIENDLY: Color = Color("#6bc9a6")  # Known/Friendly — soft green
 const ENTITY_COLOR_POI: Color = Color("#e8c547")       # Person of Interest — warm amber