chore(frontend): migrate from npm to Bun for dependency management and scripts

- Updated README to replace npm commands with Bun equivalents.
- Added `bun.lock` file to track Bun-managed dependencies.

.github/workflows/README.md

@@ -41,7 +41,7 @@ To enable CI/CD workflows:
 - Runs on: Push to main/develop, PRs affecting frontend code
 - Tests: Frontend unit tests (Jest)
 - Coverage: Uploads to Codecov
-- Fast: Uses npm cache
+- Fast: Uses bun cache
 
 ### `e2e-tests.yml`
 - Runs on: All pushes and PRs