Add vtk-mcp-client CLI and comprehensive tool tests

- src/vtk_mcp/client.py: new HTTP client covering all 24 MCP tools as
  Click subcommands (info, search, doc, synopsis, role, inheritance,
  methods, semantic-methods, method, module, module-classes, metadata,
  version, search-docs, search-examples, validate, validate-import,
  list-tools); --json flag for raw output on every command
- pyproject.toml: register vtk-mcp-client entry point
- tests/test_tools.py: 41 unit tests covering all docs/search/validation
  tool functions via an in-memory VTKAPIIndex; retriever tests use a
  MagicMock so vtk_index is not required

Author: vicentebolea

pyproject.toml

@@ -36,6 +36,7 @@ dependencies = [
 
 [project.scripts]
 vtk-mcp = "vtk_mcp.__main__:main"
+vtk-mcp-client = "vtk_mcp.client:main"
 
 [project.optional-dependencies]
 retrieval = [