Apply ruff check --fix and ruff format across all Python files to
pass CI pipeline. Remove unused imports (os, sys), fix f-strings
without placeholders. Update README to reflect sync-roster Lambda,
corrected shared layer path, and current project structure.
- Add sync-roster Lambda that auto-syncs employee roster from Slack
channel membership (runs Monday 6:55am ET before menu publish)
- Move FormApiKey from CloudFormation parameter/env var to Secrets
Manager (meal-order-manager/form-api-key) per security conventions
- Add Slack app manifest with required bot scopes
- Add get_channel_members() and get_user_info() to shared Slack module
- Add Lambda function ARN outputs to CloudFormation
- Add log group for sync-roster Lambda (60-day retention)
