This commit adds a new configuration option `max_request_line_size` that allows
users to increase the HTTP request line size limit. This is particularly useful
for handling very long continuation tokens that can cause 414 (URI Too Long) errors.

Changes:
- Add `max_request_line_size` property to Config class
- Configure Kemal server to use the custom limit if specified
- Document the option in config.example.yml with recommendations
- Add examples in docker-compose.yml for both YAML and env var configuration

The default behavior remains unchanged (8KB limit) unless explicitly configured.
This provides a solution for users experiencing 414 errors without affecting
existing installations.