chore: set up pre-commit framework with general hooks

Add .pre-commit-config.yaml with pre-commit-hooks v5.0.0 (trailing
whitespace, end-of-file fixer, yaml/json checks, large file guard,
merge conflict detection). Add minimal pyproject.toml. Auto-fix
trailing whitespace and missing end-of-file newlines across the
codebase.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -0,0 +1,4 @@
+[project]
+name = "kicad-mcp-server"
+version = "2.1.0"
+requires-python = ">=3.10"