Add basic navigation for routing

[sumedhx]

Currently, the app requires users to manually enter URL paths (e.g. /preview, /upload) to navigate between pages. There is no in-app navigation UI.

There could be basic navigation layout shown when the user is logged in. This would allow users to easily move between pages like :

• preview (to edit )
• upload (to upload a new resume)

@Nutlope @riccardogiorato