- Define Adapter interface for wrapping external tools
- Add CheckAvailability, Install, GenerateConfig, Execute, ParseOutput
- Add SubprocessExecutor for running tools as child processes
- Add ToolOutput and Violation types
- Adapters will wrap tools like ESLint, Prettier, etc.

- Add Registry for managing available engines
- Support lazy initialization (create on first Get)
- Thread-safe with RWMutex
- Global registry accessible via Global()
- MustRegister helper for init() registration

- Add tests for Rule helper methods (GetString, GetInt, etc.)
- Add tests for Violation.String() formatting
- Add tests for Registry (register, get, lazy init, duplicates)
- All tests passing

- Add Adapter with CheckAvailability, Install, GenerateConfig
- Support local (tools dir) and global ESLint installation
- Auto-install via npm if not found
- Add config generator for pattern/length/style rules
- Map Symphony rules to ESLint rules:
  - Pattern: id-match, no-restricted-syntax, no-restricted-imports
  - Length: max-len, max-lines, max-params, max-lines-per-function
  - Style: indent, quotes, semi

- Implement execute() to run ESLint with generated config
- Write config to temp file, execute ESLint with --format json
- Support both local (tools dir) and global ESLint
- Implement parseOutput() to convert ESLint JSON to violations
- Map ESLint severity (0/1/2) to string (info/warning/error)

Pattern Engine:
- Validates naming conventions (id-match)
- Detects forbidden patterns (no-restricted-syntax)
- Controls imports (no-restricted-imports)
- Delegates to ESLint adapter

Length Engine:
- Validates line length (max-len)
- Validates file length (max-lines)
- Validates function length (max-lines-per-function)
- Validates parameter count (max-params)
- Delegates to ESLint adapter

Both engines:
- Auto-install ESLint if not found
- Support JavaScript/TypeScript/JSX/TSX
- Filter files by language selector
- Convert adapter violations to core violations

- Add builtin.go to register engines in init()
- Add unit tests for ESLint config generation
- Add unit tests for ESLint output parsing
- All tests passing

- Add bad-naming.js with intentional violations
- Add good-code.js with correct code
- Add pattern engine integration test
- Test validates naming conventions via ESLint
- Test skips if ESLint not available

- Add Adapter with CheckAvailability, Install
- Support --check mode (validation) and --write mode (autofix)
- Generate .prettierrc.json from style rules
- Map style options: tabWidth, semi, singleQuote, trailingComma
- Parse Prettier output (file list when formatting needed)
- Auto-install via npm if not found

Style Engine:
- Validates with ESLint (indent, quotes, semi rules)
- Auto-fixes with Prettier (--write mode)
- Supports diff preview before applying fixes

Features:
- Validation: ESLint respects user config
- Autofix: Prettier for fast formatting
- Diff generation: Preview changes before applying
- Two-tier strategy: validate strictly, fix quickly

Autofix methods:
- Autofix(): Apply Prettier formatting
- GenerateDiff(): Preview changes without writing

- Register style engine in builtin.go
- Add Prettier config generation tests
- Add bad-style.js (unprettified code)
- Add good-style.js (prettified code)
- All tests passing