❇️ RZE-2500001: add backend using honojs

[xkeshav]

Is your feature request related to a problem? Please describe.
Add /backend folder and start using hono for backend

Describe the solution you'd like
Add basic user and subscription documents and with secure headers and validation using open API

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

[xkeshav]