Feat: JSON and YAML Validator and AutoFix Tools

[pozgo]

Developer Tools Section

• New Tools page accessible from the dashboard with dedicated tiles
• YAML Validator - Full-featured YAML validation, formatting, and auto-fix tool:
  • Monaco Editor with YAML syntax highlighting
  • Validate YAML syntax with line/column error reporting
  • Format/beautify YAML documents
  • Auto-fix common issues: tabs→spaces, odd indentation, trailing whitespace, colon-in-value quoting
  • Diff view showing exactly what auto-fix changed
  • Copy output to clipboard
• JSON Validator - Comprehensive JSON validation, formatting, and repair tool:
  • Monaco Editor with JSON syntax highlighting
  • Validate JSON syntax with line/column error reporting
  • Format/beautify and minify JSON
  • Auto-fix using jsonrepair library: trailing commas, comments, mismatched braces, structural issues
  • Diff view showing exactly what auto-fix changed
  • Copy output to clipboard

Technical Details

New Frontend Components

• ToolsPage.jsx - Tools hub with navigation tiles
• YamlValidator.jsx - YAML tool with js-yaml integration
• JsonValidator.jsx - JSON tool with jsonrepair integration
• shared/ToolLayout.jsx - Common page wrapper for tools
• shared/ValidationResult.jsx - Error/success display component

New Dependencies (Frontend)

• @monaco-editor/react - VS Code editor React wrapper
• js-yaml - YAML parsing and formatting
• jsonrepair - JSON auto-fix and repair

Routes

• /tools - Tools hub page
• /tools/yaml - YAML Validator
• /tools/json - JSON Validator