Align repo config with global development standards

- Add missing tsconfig strictness flags (noUncheckedIndexedAccess,
  exactOptionalPropertyTypes, noImplicitOverride,
  noPropertyAccessFromIndexSignature) and fix all resulting type errors
- Replace ESLint/Prettier with oxlint 1.48.0 and oxfmt 0.33.0
- Pin all frontend and backend dependencies to exact versions
- Pin GitHub Actions to SHA hashes with persist-credentials: false
- Fix CI Python version mismatch (3.12 -> 3.14) and ruff target-version
- Add vitest 4.0.18 with jsdom environment for frontend testing
- Add ty 0.0.17 for Python type checking (non-blocking in CI)
- Add actionlint and zizmor CI job for workflow linting and security audit
- Add Dependabot config for npm, pip, and github-actions
- Update CLAUDE.md and pre-commit hooks to reflect new tooling
- Ignore Claude Code sandbox artifacts in gitignore

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

frontend/src/components/BossDefeatModal.tsx

@@ -10,14 +10,11 @@ interface BossDefeatModalProps {
   starterName?: string | null
 }
 
-function matchVariant(
-  labels: string[],
-  starterName?: string | null
-): string | null {
+function matchVariant(labels: string[], starterName?: string | null): string | null {
   if (!starterName || labels.length === 0) return null
   const lower = starterName.toLowerCase()
   const matches = labels.filter((l) => l.toLowerCase().includes(lower))
-  return matches.length === 1 ? matches[0] : null
+  return matches.length === 1 ? (matches[0] ?? null) : null
 }
 
 export function BossDefeatModal({
@@ -46,14 +43,13 @@ export function BossDefeatModal({
   )
   const showPills = hasVariants && autoMatch === null
   const [selectedVariant, setSelectedVariant] = useState<string | null>(
-    autoMatch ?? (hasVariants ? variantLabels[0] : null)
+    autoMatch ?? (hasVariants ? (variantLabels[0] ?? null) : null)
   )
 
   const displayedPokemon = useMemo(() => {
     if (!hasVariants) return boss.pokemon
     return boss.pokemon.filter(
-      (bp) =>
-        bp.conditionLabel === selectedVariant || bp.conditionLabel === null
+      (bp) => bp.conditionLabel === selectedVariant || bp.conditionLabel === null
     )
   }, [boss.pokemon, hasVariants, selectedVariant])
 
@@ -72,9 +68,7 @@ export function BossDefeatModal({
       <div className="relative bg-white dark:bg-gray-800 rounded-lg shadow-xl max-w-md w-full mx-4">
         <div className="px-6 py-4 border-b border-gray-200 dark:border-gray-700">
           <h2 className="text-lg font-semibold">Battle: {boss.name}</h2>
-          <p className="text-sm text-gray-500 dark:text-gray-400">
-            {boss.location}
-          </p>
+          <p className="text-sm text-gray-500 dark:text-gray-400">{boss.location}</p>
         </div>
 
         {/* Boss team preview */}
@@ -104,11 +98,7 @@ export function BossDefeatModal({
                 .map((bp) => (
                   <div key={bp.id} className="flex flex-col items-center">
                     {bp.pokemon.spriteUrl ? (
-                      <img
-                        src={bp.pokemon.spriteUrl}
-                        alt={bp.pokemon.name}
-                        className="w-10 h-10"
-                      />
+                      <img src={bp.pokemon.spriteUrl} alt={bp.pokemon.name} className="w-10 h-10" />
                     ) : (
                       <div className="w-10 h-10 bg-gray-200 dark:bg-gray-700 rounded-full" />
                     )}
@@ -158,9 +148,7 @@ export function BossDefeatModal({
 
             {!hardcoreMode && (
               <div>
-                <label className="block text-sm font-medium mb-1">
-                  Attempts
-                </label>
+                <label className="block text-sm font-medium mb-1">Attempts</label>
                 <input
                   type="number"
                   min={1}