fix(simulation): address PR #37 review — doc corrections, race fix, marker cleanup

Hoshe review (4 items):
- types.rs: doc comment "Current: 6" → "Current: 9"
- dialogue.rs: walk-away doc duplicated numbering (items 4-5 were 2-3)
- test_world/mod.rs: comment "Reset plates at 49-51" → "49-55"
- content_scaling.rs: magic number 51 → constants::RESET_PLATE_STABLE_IDS.1

Tyre review (3 items):
- knowledge/types.rs: guard comments on decrement() floor at Hostile
- input.rs: TeleportToHub now clears ConfrontationDelivered marker
- content_scaling.rs: same magic number fix (covered above)

Additional:
- content_runtime.rs: barrier-based shutdown handshake fixes TCP RST
  race condition under parallel test execution
- dialogue_room.rs: clippy type_complexity allow on NPCS tuple array

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

server/src/knowledge/types.rs

@@ -134,14 +134,14 @@ impl RelationshipState {
     ///
     /// Friendly → Known → PersonOfInterest → Hostile.
     /// Unknown stays Unknown (can't confront a stranger meaningfully).
-    /// Hostile stays Hostile (already worst state).
+    /// Hostile stays Hostile — floor, does not wrap or panic.
     pub fn decrement(self) -> Self {
         match self {
             Self::Friendly => Self::Known,
             Self::Known => Self::PersonOfInterest,
             Self::PersonOfInterest => Self::Hostile,
-            Self::Unknown => Self::Unknown,
-            Self::Hostile => Self::Hostile,
+            Self::Unknown => Self::Unknown,       // no-op: can't confront a stranger
+            Self::Hostile => Self::Hostile,        // floor: already worst state
         }
     }
 }