feat(simulation): Sprint 6 Touch — stance, tile presence, verbs, protocol v6

Implements the core Sprint 6: Touch systems across 5 tickets:

- #449 ObserverSnapshot v6: add player_stance (MovementStance) and
  player_inventory (Vec<InventoryItem>) wire fields with serde defaults
  for backward compatibility. Bump PROTOCOL_VERSION 5→6.

- #417 Stance system: Sprint/Walk/Careful/Crouch movement stance with
  tick-based speed (1/2/3/4 ticks per move), monologue rate multipliers,
  and PlayerMoveCooldown component. ToggleStanceUp/Down player actions.

- #420 TilePresence: posture-layer collision system allowing same-tile
  occupancy for different layers (Standing/Prone/Seated/Fixture).
  Layer-based collision in validate_movement.

- #421 ObjectType component: Readable/Container/Terminal/Door/Pickup/
  Furniture types with Phase 1 verb sets computed from type + proximity.

- #422 Phase 2 verb filter: KG-gated observer-side verb processing —
  POI priority flips, Confront injection at KnowsDetails+, contradiction
  marking, archetype-specific label relabeling (Smuggler/Detective).

217 unit tests + 17 integration tests passing. All MessagePack fixtures
regenerated for v6 wire format.

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

server/src/perception/observer/tests.rs

@@ -1,4 +1,5 @@
 use super::*;
+use crate::knowledge::types::KnowledgeState;
 use crate::knowledge::{EntityRegistry, KnowledgeGraph};
 use crate::perception::query::{ActivePerceptionMode, VisibilityGeometry};
 use crate::perception::vision_cone::Facing;
@@ -56,7 +57,7 @@ fn player_always_visible_in_snapshot() {
 
     let buffer = world.resource::<SnapshotBuffer>();
     let snapshot = buffer.snapshot.as_ref().expect("snapshot should exist");
-    assert_eq!(snapshot.version, 5);
+    assert_eq!(snapshot.version, 6);
     assert_eq!(snapshot.entities.len(), 1);
     assert!(matches!(snapshot.entities[0].kind, EntityKind::Player));
     assert_eq!(snapshot.entities[0].observation, EntityVisibility::Visible);
@@ -632,3 +633,54 @@ fn poi_interaction_gets_observe_first_priority() {
     assert_eq!(interaction.verbs[1].kind, VerbKind::Talk);
     assert_eq!(interaction.verbs[1].priority, 2);
 }
+
+// -----------------------------------------------------------------------
+// v6 field tests (Hoshe QA, Sprint 6 — #449)
+// -----------------------------------------------------------------------
+
+#[test]
+fn snapshot_v6_fields_default_through_pipeline() {
+    // Until #417 (stance) and #424 (inventory) wire up the components,
+    // the observer system should produce Walk stance and empty inventory.
+    let mut world = setup_world(32, 32);
+    world.spawn((
+        PlayerCharacter,
+        TilePosition::new(16, 16, 0),
+        Facing::default(),
+        KnowledgeGraph::new(),
+        NearbyInteractionBuffer::default(),
+        MonologueBuffer::default(),
+    ));
+
+    run_observer_pipeline(&mut world);
+
+    let buffer = world.resource::<SnapshotBuffer>();
+    let snapshot = buffer.snapshot.as_ref().expect("snapshot should exist");
+
+    assert_eq!(snapshot.version, 6, "should be protocol v6");
+    assert_eq!(snapshot.player_stance, MovementStance::Walk, "default stance is Walk");
+    assert!(snapshot.player_inventory.is_empty(), "default inventory is empty");
+}
+
+#[test]
+fn snapshot_v6_version_is_protocol_version() {
+    let mut world = setup_world(32, 32);
+    world.spawn((
+        PlayerCharacter,
+        TilePosition::new(16, 16, 0),
+        Facing::default(),
+        KnowledgeGraph::new(),
+        NearbyInteractionBuffer::default(),
+        MonologueBuffer::default(),
+    ));
+
+    run_observer_pipeline(&mut world);
+
+    let buffer = world.resource::<SnapshotBuffer>();
+    let snapshot = buffer.snapshot.as_ref().unwrap();
+    assert_eq!(
+        snapshot.version,
+        crate::bridge::types::PROTOCOL_VERSION,
+        "snapshot version must match PROTOCOL_VERSION constant"
+    );
+}