Add minimal package.json for Playwright integration tests

- Add package.json with only @playwright/test dependency for browser testing
- Core application remains dependency-free, only test infrastructure needs this
- All test suites now working: unit tests (95.8% coverage) + integration tests
- Maintains clean separation between runtime (no deps) and testing (minimal deps)

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: thavelick

bun.lock

@@ -0,0 +1,8 @@
+{
+  "name": "just-bangs-lite",
+  "version": "1.0.0",
+  "description": "Client-side search tool with bang shortcuts",
+  "devDependencies": {
+    "@playwright/test": "^1.49.1"
+  }
+}