fix: remove build artifacts and coverage files from tracking

- Remove compiled binary 'api' from git tracking
- Remove 'cover.out' coverage file from git tracking
- Update .gitignore to include 'api' and 'cover.out'
- Clean up temporary files: coverage.out, dump.rdb

.gitignore

@@ -1,4 +1,6 @@
 .DS_Store
 dump.rdb
 coverage.out
+cover.out
+api
 *.log