Add post-game completion rule option

Add postGameCompletion toggle to nuzlocke rules so players can indicate
whether a run ends after the Champion or continues into post-game. Adds
a new "Completion" category section in rules configuration with a green
badge color.

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

frontend/src/types/rules.ts

@@ -11,6 +11,9 @@ export interface NuzlockeRules {
   hardcoreMode: boolean
   levelCaps: boolean
   setModeOnly: boolean
+
+  // Completion
+  postGameCompletion: boolean
 }
 
 export const DEFAULT_RULES: NuzlockeRules = {
@@ -26,13 +29,16 @@ export const DEFAULT_RULES: NuzlockeRules = {
   hardcoreMode: false,
   levelCaps: false,
   setModeOnly: false,
+
+  // Completion
+  postGameCompletion: false,
 }
 
 export interface RuleDefinition {
   key: keyof NuzlockeRules
   name: string
   description: string
-  category: 'core' | 'difficulty'
+  category: 'core' | 'difficulty' | 'completion'
 }
 
 export const RULE_DEFINITIONS: RuleDefinition[] = [
@@ -102,4 +108,13 @@ export const RULE_DEFINITIONS: RuleDefinition[] = [
       'The game must be played in "Set" battle style, meaning you cannot switch Pokémon after knocking out an opponent.',
     category: 'difficulty',
   },
+
+  // Completion
+  {
+    key: 'postGameCompletion',
+    name: 'Post-Game Completion',
+    description:
+      'The run continues into post-game content instead of ending after the Champion is defeated.',
+    category: 'completion',
+  },
 ]