Migrate polar-app and polar-adapters to monorepo

[birkjernstrom]

trafficstars

Move the mobile app (polar-app) and adapter repos (polar-adapters) into the core polar repository as a monorepo setup.

Benefits:

• Use internal SDK instead of troublesome Speakeasy client
• Keep everything in sync more easily
• Simplify onboarding for new team members (Sebastian starting next week)
• Better developer experience with TurboRepo for TypeScript projects

Scope:

• Migrate polar-app repository
• Migrate polar-adapters repository
• Set up TurboRepo configuration
• Update CI/CD pipelines
• Update documentation and README files