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/Layout.tsx

@@ -55,12 +55,7 @@ export function Layout() {
                 className="p-2 rounded-md hover:bg-gray-100 dark:hover:bg-gray-700"
                 aria-label="Toggle menu"
               >
-                <svg
-                  className="w-6 h-6"
-                  fill="none"
-                  stroke="currentColor"
-                  viewBox="0 0 24 24"
-                >
+                <svg className="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                   {menuOpen ? (
                     <path
                       strokeLinecap="round"