Add jsinspect-plus structural duplication gate, extract shared helpers

Add jsinspect-plus (AST-based structural duplication detector) to pnpm
check with threshold 50 / min 3 instances. Fix all findings:

- Extract condition icon/color maps to shared condition-styles.ts
- Extract useClickOutside hook (5 components)
- Extract dispatchAction + resolveAndRename in use-encounter
- Extract runEncounterAction in application layer (13 use cases)
- Extract findCombatant helper in domain (9 functions)
- Extract TraitSection in stat-block (4 trait rendering blocks)
- Extract DialogHeader in dialog.tsx (4 dialogs)

Net result: -263 lines across 40 files.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/domain/src/edit-combatant.ts

@@ -1,5 +1,11 @@
 import type { DomainEvent } from "./events.js";
-import type { CombatantId, DomainError, Encounter } from "./types.js";
+import {
+	type CombatantId,
+	type DomainError,
+	type Encounter,
+	findCombatant,
+	isDomainError,
+} from "./types.js";
 
 export interface EditCombatantSuccess {
 	readonly encounter: Encounter;
@@ -30,17 +36,9 @@ export function editCombatant(
 		};
 	}
 
-	const index = encounter.combatants.findIndex((c) => c.id === id);
-
-	if (index === -1) {
-		return {
-			kind: "domain-error",
-			code: "combatant-not-found",
-			message: `No combatant found with ID "${id}"`,
-		};
-	}
-
-	const oldName = encounter.combatants[index].name;
+	const found = findCombatant(encounter, id);
+	if (isDomainError(found)) return found;
+	const oldName = found.combatant.name;
 
 	return {
 		encounter: {