feat: add run_tools_batch for read-only MCP workflows

[QuantumByte-01]

Summary

• Adds a new MCP tool run_tools_batch for batching read-only tool invocations in one request.
• Supports MVP read-only tools: list_estimators, describe_estimator, get_available_tags, list_available_data.
• Returns ordered per-operation results with index, tool, success, and either result or error.

Why

Agentic flows often make multiple read-only calls in sequence. Batching these calls reduces round-trips while keeping the MVP scope safe (no mutating tools).

Changes

• Added src/sktime_mcp/tools/batch.py with run_tools_batch_tool.
• Wired tool into server.py (list_tools schema + call_tool dispatcher).
• Exported helper in src/sktime_mcp/tools/__init__.py.
• Added unit tests in tests/test_batch_tools.py for success, malformed operations, and unsupported tools.

Validation

• python -m ruff check src/sktime_mcp/tools/batch.py src/sktime_mcp/tools/__init__.py src/sktime_mcp/server.py tests/test_batch_tools.py
• python -m pytest tests/test_batch_tools.py -q

Closes #408

[Shashankss1205]

Since this was opened the tool surface was consolidated to 26 tools (#270, #460) and three of the four tools this batcher wraps (list_estimators, describe_estimator, get_available_tags) were removed in favour of query_registry/describe_component; server.py was also rewritten. The direction is to avoid new meta/bespoke tools, so closing; MCP clients can already issue read-only calls concurrently on their side.