feat: implement configurable resource limits for hosts

- Added a new reusable component `ResourceLimitsSelector` for selecting memory, CPU, and disk limits with preset and custom input options.
- Integrated resource limits selection in the create host dialog and host details page, allowing for editing and displaying resource limits.
- Introduced a PATCH API endpoint to update resource limits for stopped hosts.
- Updated database schema to allow nullable resource limit fields, enabling "unlimited" semantics.
- Enhanced frontend forms to support intuitive resource limit selection and validation.
- Documented implementation decisions, context, and research findings related to resource limits configuration.

Author: ZaneL1u