feat(simulation): contraband detection + dialogue confidence gate (D-075) (#425, #524)

Contraband detection (Task #425, D-065):
- New module: simulation/contraband.rs — NPC scan checks carried items
  against the KnowledgeGraph confidence gate. NPCs with Authority access
  can initiate a scan; scan outcome depends on item CarriedBy + KG entry.
- Adds ContrabandScanResult event type and ContrabanEntry component.
- Wired into simulation/mod.rs module list.

Dialogue confidence gate (Task #524, D-075 — OQ-18 resolution):
- relationship_to_trust() gains confidence parameter (KnowledgeConfidence).
- Trust tier mapping: (Friendly, KnowsDetails+)→Secret, (Friendly|Known,
  KnowsOf+)→Real, otherwise Surface. Access tier (Layer 1) unchanged.
- Caller process_talk_interaction passes observer KG confidence_of target.
- Resolves OQ-18: confidence co-gates TrustTier, not AccessTier.

Supporting changes:
- decisions/content.md: add D-075 (16 decisions, dated 2026-02-19)
- knowledge/types.rs: expose KnowledgeConfidence comparison helpers
- knowledge/registry.rs: minor API polish
- bridge/types.rs: ContrabandScanResult wire type
- bridge/text_renderer.rs: render contraband scan status
- perception/observer: include carried item count in snapshot
- npc/mod.rs: NPC scan range constant, authority flag

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

server/src/knowledge/registry.rs

@@ -77,7 +77,8 @@ impl EntityRegistry {
         assert!(
             target >= self.next_id,
             "cannot reserve backwards: next_id={}, target={}",
-            self.next_id, target
+            self.next_id,
+            target
         );
         self.next_id = target;
     }

server/src/knowledge/types.rs

@@ -140,8 +140,8 @@ impl RelationshipState {
             Self::Friendly => Self::Known,
             Self::Known => Self::PersonOfInterest,
             Self::PersonOfInterest => Self::Hostile,
-            Self::Unknown => Self::Unknown,       // no-op: can't confront a stranger
-            Self::Hostile => Self::Hostile,        // floor: already worst state
+            Self::Unknown => Self::Unknown, // no-op: can't confront a stranger
+            Self::Hostile => Self::Hostile, // floor: already worst state
         }
     }
 }