fix(simulation): address PR #26 review comments (13 items)

Warnings fixed:
- Add WalkAway to all_player_action_variants_roundtrip test
- Warn and skip on unresolvable speaker_entity_id (was silent 0)
- Change MonologueState.shown_ids from Vec to HashSet (O(1) lookup)
- Add cross-plugin ordering: trigger_recognition_monologue after
  detect_anomalies (latent determinism bug)
- Add TODO for unreachable Secret trust tier

Suggestions addressed:
- Server-side range check for Talk verb in handle_talk (CLOSE_RANGE)
- Emit IncompleteInteraction before overwriting ActiveDialogue
- Add different_seed_produces_different_replay determinism test
- Replace panic with assert for unknown fixture naming convention
- Fix duplicate "Observe" label: ExamineNpc now uses "Examine NPC"
- Change DialogueCooldownTracker.used from Vec to BTreeMap (D-041)
- Add .after(process_talk_interaction) to process_walk_away ordering
- Collapse dead conditional in main.rs (both branches identical)

468 tests pass, 0 failures.

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

server/src/simulation/interaction.rs

@@ -219,7 +219,7 @@ pub fn compute_nearby_interactions(
                 });
                 verbs.push(VerbOption {
                     kind: VerbKind::ExamineNpc,
-                    label: "Observe".into(),
+                    label: "Examine NPC".into(),
                     priority: 2,
                     available: true,
                 });
@@ -227,7 +227,7 @@ pub fn compute_nearby_interactions(
                 // Mid range: only Examine NPC (Talk requires close range)
                 verbs.push(VerbOption {
                     kind: VerbKind::ExamineNpc,
-                    label: "Observe".into(),
+                    label: "Examine NPC".into(),
                     priority: 1,
                     available: true,
                 });