feat: add get_frappe_repo_path with tests

[Shekhar0109]

✨ Summary

This PR introduces a utility function get_frappe_repo_path to centralize and standardize how the Frappe repository path is determined across the project.

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🔧 Changes

• Added frappe_manager/paths.py containing:
  • get_frappe_repo_path() → returns the repo path from FRAPPE_REPO_PATH environment variable, defaults to ./repos/frappe.
• Updated frappe_manager/__init__.py to use the new function instead of hardcoding the path.
• Added unit tests in test/test_paths.py to validate both default and custom env var behaviors.
• Updated pyproject.toml → added pytest as a dev dependency for testing.
• Regenerated poetry.lock with new dependencies.

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✅ Tests

• Default Path Test → ensures fallback to ./repos/frappe when FRAPPE_REPO_PATH is not set.
• Custom Env Path Test → ensures custom path is correctly picked from the FRAPPE_REPO_PATH environment variable.
• All tests executed successfully:

pytest -q
2 passed in 3.00s

Notes

This change makes the repository path configurable and avoids hardcoded values.
Backward compatible: if FRAPPE_REPO_PATH is not set, defaults to ./repos/frappe.

Labels

• enhancement
• tests

Checklist

• PR ready for review ✅
• Documentation updated ✅
• Tests added / updated ✅

Closes #250

[wasup-yash]

This PR does not fully solve the reqested issue which is asked in the Issue description. (not official reviewer)