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>

.beans/nuzlocke-tracker-9vny--add-dependabot-config.md

@@ -0,0 +1,18 @@
+---
+# nuzlocke-tracker-9vny
+title: Add Dependabot config
+status: completed
+type: task
+priority: normal
+created_at: 2026-02-16T19:13:50Z
+updated_at: 2026-02-16T19:24:15Z
+parent: nuzlocke-tracker-a5es
+---
+
+No .github/dependabot.yml exists. Global standards require Dependabot with 7-day cooldowns and grouped updates.
+
+## Checklist
+- [ ] Create .github/dependabot.yml
+- [ ] Configure for npm (frontend), pip (backend), and github-actions
+- [ ] Set 7-day schedule intervals
+- [ ] Group minor/patch updates