* Upgrade ESLint and related configurations to version 9
- Update ESLint to version 9.19.0
- Migrate ESLint configurations to flat config format
- Remove deprecated ESLint config files
- Update package dependencies and configurations
- Simplify ESLint setup across packages
- Remove unnecessary ESLint config blocks from package.json files
- Improved CI caching with Turborepo tasks
- Removed duplicate styles
* Refactor core to use a flexible registry pattern
- Introduce a new registry mechanism for mailer providers
- Extract mailer provider enum to a separate file
- Implement dynamic mailer loading using a registry
- Update package dependencies and exports
- Improve modularity and extensibility of mailer implementation
* Refactor monitoring and billing services to use a flexible registry pattern
- Introduce a shared registry mechanism for dynamic service loading
- Replace static switch-based implementations with a registry-based approach
- Update instrumentation, CMS, and monitoring services to use the new registry
- Improve modularity and extensibility of service implementations
- Add Zod-based type-safe provider validation
* Simplify async registration in monitoring and billing services
- Remove unnecessary async wrappers for no-op registrations
- Update type definitions to support both async and sync registration functions
- Standardize registration approach for Paddle and Sentry providers
* Remove Tailwind package from packages where it is not being needed
* Remove Tailwind config references from pnpm-lock.yaml
* Update instrumentation registry to support dynamic monitoring providers
- Modify type definition to use NonNullable MonitoringProvider
- Import MonitoringProvider type from get-monitoring-provider
- Enhance type safety for instrumentation registration
