dsh-ptc-cordis-preset: Add Creative Mode to DSH PTC

# Introduction When developing with DSH (DeepSeek Harness), there are two types of tasks that are very common. One type is tool orchestration: using the Code Mode SDK to write a `run_code` program to combine multiple tool calls into a single execution. The other type is creative work centered around the runtime: inspecting the live runtime, defining and experimenting with dynamic plugin packages, and even creating new agent presets. These two capabilities currently belong to two built-in presets in DSH: the built-in PTC preset (ID is `code`, renamed to `ptc` starting from dsh 0.1.2) provides Code Mode orchestration; the built-in creative preset (`cordis`) provides self-referential Cordis tools...