feat(schema): implement Phase 14 LazySchema for recursive types

[viniciusdacal]

Summary

• Add LazySchema with deferred resolution — getter is called on first use, not at construction
• Support recursive type definitions (e.g., tree nodes with self-referencing children)
• JSON Schema output delegates to resolved inner schema, works with .id() for $ref/$defs
• Validates deeply nested recursive data with proper error paths

Test plan

• Deferred resolution — getter not called until first parse
• Recursive tree node parsing (4 levels deep)
• JSON Schema with $ref for named lazy schemas
• Deep recursive validation
• Rejects invalid data in recursive structures with correct path
• 249 tests passing across 53 test files, no regressions

🤖 Generated with Claude Code

[viniciusdacal]

Post-PR Review

Overview: Phase 14 adds LazySchema for recursive type definitions. Clean, minimal implementation (40 lines) that leverages existing infrastructure.

Code Quality: LazySchema follows established patterns — extends Schema, implements _parse/_schemaType/_toJSONSchema/_clone. Uses memoized getter pattern for deferred resolution.

Test Coverage: 5 tests covering deferred resolution, recursive parsing, JSON Schema $ref output, deep nesting, and error path validation. All 249 tests pass.

No issues found. The implementation is elegant — LazySchema simply delegates to the resolved inner schema, and the existing infrastructure handles everything else (recursive $ref, error paths, pipeline execution).