fix: use TypeScript compiler API for interface parsing in swagger.ts

[Many0nne]

Summary

• Replace the regex-based extractInterfaceProperties() with AST traversal using ts.createSourceFile() and ts.forEachChild()
• Exact interface name matching (no regex injection risk)
• Correctly handles readonly properties, optional fields (?), nested objects ({ foo: string }), and generic types (Record<string, string>)
• Extend typeToOpenAPISchema() to map generic types (containing <) to { type: 'object' }

Test plan

• All 171 existing tests pass
• Swagger spec generation works correctly for standard interfaces

Closes #24

🤖 Generated with Claude Code