Implement ASTGenerator

[leogdion]

Phase

Phase 3: Input/Output Handlers

Specification

Create AST generator that wraps SyntaxParser to produce JSON AST from Swift code.

Acceptance Criteria

• ASTGenerator struct created
• generateAST() uses SyntaxParser.parse()
• TreeNode array formatted as JSON
• JSONEncoder uses prettyPrinted and sortedKeys
• Error handling for encoding failures
• Code follows one-type-per-file organization

Dependencies

• Depends on: Implement AnalyzerConfiguration and AnalyzerError #110

Files to Create/Modify

• Sources/AiSTKit/ASTGenerator.swift

Related Documentation

• skit-analyze-plan.md