fix(sdk-minimal): make the SDK model argument authoritative

Stop narrowing the standalone DeepSeek adapter to a DSH_MODEL-derived one-entry catalog. The direct adapter already accepts model ids outside its advisory catalog, so retain only the DSH_CONTEXT_WINDOW fallback and let the JSON-RPC initialize model be the single runtime selection.

Remove model mirroring from minimal.py and the packaged smoke. The keyless process now initializes deepseek-v4-pro without DSH_MODEL, while the packaged scenario continues to use its unlisted smoke-model; together they prove both cataloged and arbitrary SDK model arguments reach the adapter directly.

Update the bundle, tutorial, SDK/example references, and owning Agent Notes to keep DSH_MODEL only as minimal.py's optional default input, never as a second value callers must synchronize.

docs/user/guide/python-sdk.md

@@ -61,7 +61,6 @@ with DeepSeekHarness(
     cwd=str(workspace),
     dsh_home=str(dsh_home),
     profile="sdk-minimal",
-    env={"DSH_MODEL": "deepseek-v4-flash"},
 ) as harness:
     result = harness.run(
         "Inspect the repository and fix the failing tests.",