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/StatCard.tsx

@@ -1,7 +1,7 @@
 interface StatCardProps {
   label: string
   value: number
-  total?: number
+  total?: number | undefined
   color: string
 }
 
@@ -22,10 +22,7 @@ export function StatCard({ label, value, total, color }: StatCardProps) {
       <div className="text-2xl font-bold text-gray-900 dark:text-gray-100">
         {value}
         {total !== undefined && (
-          <span className="text-sm font-normal text-gray-500 dark:text-gray-400">
-            {' '}
-            / {total}
-          </span>
+          <span className="text-sm font-normal text-gray-500 dark:text-gray-400"> / {total}</span>
         )}
       </div>
       <div className="text-sm text-gray-600 dark:text-gray-400">{label}</div>