v0.3.0 - Nested objects decoding

✨ Added

Nested object decoding
You can now write YAML-style nested TOON:

user:
id: 1
name: Manoj

Better internal error messages (line numbers, row contexts)

Tightened row-count validation for:

primitive arrays

list blocks

tabular blocks

🛠 Improved

Decoder internals refactored to be cleaner and fully indentation-aware

PHPStan clean run (0 errors) with updated rules

🧪 Testing

Added round-trip tests for nested structures

100% test suite passing (24 tests, 46 assertions)