fix(repo): remove tracked binaries and logs and guard against re-adding

[DivyashreeR008]

Fixes #167

Problem:
Build artifacts and local logs were committed even though .gitignore already has rules for them. The five tracked files are services/attendance-service/attendance-service.exe (23 MB), services/notification-go-service/notification.exe (9.7 MB), frontend/stdout.log, frontend/stderr.log and frontend/tsconfig.tsbuildinfo. They were added before the ignore rules, so gitignore does not apply to tracked files. The binaries are Windows PE files that are useless on ubuntu-latest and in Docker images, they bloat the pack to ~20 MB and every clone pays for it, and the logs can carry local paths.

Fix:

• Ran git rm --cached on the five files so they are removed from the index but stay ignored locally. Verified with git ls-files | grep -E ".exe$|.log$|tsbuildinfo" which now returns nothing.
• Added a root .dockerignore that ignores *.exe, *.log, *.tsbuildinfo and other build artifacts so they never enter an image layer when the build context is the repo root.
• Created services/lms-service/.dockerignore and updated the existing service .dockerignore files (attendance, notification, api-gateway, auth, analytics, ats, employee-python, leave) to also ignore those patterns for builds where the context is the service directory.
• Added a guard-against-binaries job to ci.yml that fails if any tracked file matches *.exe, *.log or tsbuildinfo or if any file over 1 MB is present. This catches a future accidental add. Also noted that history can be cleaned with git filter-repo/BFG if size matters and that any sensitive data in the old logs should be rotated.

Verification:

• git ls-files | grep -E ".exe$|.log$|tsbuildinfo" now returns nothing.
• python -c "import yaml; yaml.safe_load(open('docker-compose.yml'))" still passes.
• The new guard job passes on this branch and would fail if one of those files were re-added.

Fixes #167