Add type restriction rule (monolocke)

Adds allowedTypes: string[] to NuzlockeRules. When set, the encounter
selector hides non-matching Pokemon and the routes endpoint filters out
routes with no matching encounters, so only eligible locations appear.

Type picker UI in RulesConfiguration; active restriction shown in
RuleBadges. Backend accepts allowed_types query param and joins through
RouteEncounter.pokemon to filter by type.

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

frontend/src/types/rules.ts

@@ -16,8 +16,14 @@ export interface NuzlockeRules {
   egglocke: boolean
   wonderlocke: boolean
   randomizer: boolean
+
+  // Type restriction (monolocke and variants)
+  allowedTypes: string[]
 }
 
+/** Keys of NuzlockeRules that are boolean toggles (excludes array fields) */
+type BooleanRuleKeys = Exclude<keyof NuzlockeRules, 'allowedTypes'>
+
 export const DEFAULT_RULES: NuzlockeRules = {
   // Core rules
   duplicatesClause: true,
@@ -36,10 +42,13 @@ export const DEFAULT_RULES: NuzlockeRules = {
   egglocke: false,
   wonderlocke: false,
   randomizer: false,
+
+  // Type restriction - no restriction by default
+  allowedTypes: [],
 }
 
 export interface RuleDefinition {
-  key: keyof NuzlockeRules
+  key: BooleanRuleKeys
   name: string
   description: string
   category: 'core' | 'playstyle' | 'variant'