Feature/merge instantiate tools

[Shashankss1205]

Reference Issues/PRs

Independence: This PR is rebased on latest main and does not depend on #463, #466, #468, or #469. It can be merged on its own.

What does this implement/fix? Explain your changes.

Merges instantiate_estimator and instantiate_pipeline into a single unified instantiate_estimator tool.

Before: LLM clients chose between two tools:

• instantiate_estimator(estimator="ARIMA", params={...}) — single estimator
• instantiate_pipeline(components=["Detrender", "ARIMA"], params_list=[...]) — pipeline

After: One tool handles both:

• instantiate_estimator(estimator="ARIMA", params={...}) — single estimator
• instantiate_estimator(components=["Detrender", "ARIMA"], params_list=[...]) — pipeline

The tool validates that exactly one of estimator or components is provided. A single-element components list is equivalent to a single estimator. Pipeline composition validation runs automatically when components has multiple entries.

Files changed (7):

• src/sktime_mcp/tools/instantiate.py — unified API with estimator|components dispatch; backward-compat alias instantiate_pipeline_tool kept internally
• src/sktime_mcp/server.py — merged tool schema and dispatch
• src/sktime_mcp/tools/__init__.py — removed instantiate_pipeline_tool from exports
• tests/test_param_validation.py — keyword args; mutual-exclusion tests
• tests/test_codegen.py, tests/test_core.py — updated call sites
• docs/source/implementation.md — updated documentation

Does your contribution introduce a new dependency? If yes, which one?

No.

What should a reviewer concentrate their feedback on?

• Unified instantiate_estimator_tool API — mutual exclusion logic for estimator vs components
• Merged tool schema in server.py — no required fields since either estimator or components suffices
• Backward-compat alias instantiate_pipeline_tool = instantiate_estimator_tool
• New tests: test_requires_estimator_or_components, test_rejects_both_estimator_and_components

Any other comments

Rebased on latest main (1 commit, +224 / −151). 184 tests pass under make check. Ruff lint clean.

PR checklist

For all contributions

• I've added unit tests and made sure they pass locally (make check).
• I've added the tool to the online documentation in docs/source/.