enh: cleanup and organize services and storage modules.

[shsiddhant]

Pull Request Summary

Cleanup the database and organize services and storage modules.

Type of Change

Choose one or more:

• New Feature
• Code Refactor

Added

1. Add a common engine for the app.
2. Add storage modules to keep the services layer lighter.

Changed

1. Use a session factory for getting db sessions.
2. Reduce the maximum width of message bubbles.

Checklist

• Code runs without errors
• Code style and lint checks passed