DeepSeek Harness route removed

The bundled DSH route, profile and runtime have been removed. Minimal is the only supported study workflow. To use a DeepSeek-compatible API, configure the built-in API agent through workspace Connections, or use study --backend builtin with a private provider configuration.

See migration to minimal for command replacements and handling older records. The historical DSH guide remains in the 0.6.2 source.