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>

src/prompts/design.ts

@@ -1,6 +1,6 @@
 /**
  * Design prompts for KiCAD MCP server
- * 
+ *
  * These prompts guide the LLM in providing assistance with general PCB design tasks
  * in KiCAD.
  */
@@ -11,7 +11,7 @@ import { logger } from '../logger.js';
 
 /**
  * Register design prompts with the MCP server
- * 
+ *
  * @param server MCP server instance
  */
 export function registerDesignPrompts(server: McpServer): void {