[ISSUE-137] Python bindings row-based append API

[fresh-borzoni]

Purpose

Linked issue: close #137

Adds a Python append() method to enable single-row inserts with support for dict, list, and tuple input formats, providing a more ergonomic API for appending individual rows compared to batch operations.

Brief change log

• Add append() method to Python Table class with support for dict, list, and tuple input
• Implement RowInput enum with FromPyObject derive for automatic type dispatch
• Add python_to_generic_row() function to convert Python values to GenericRow with strict validation
• Add python_value_to_datum() function with type-specific conversions, optimized bytes extraction, and field-level error messages
• Add Python patterns to .gitignore to exclude __pycache__/ and *.so files
• Add usage examples and type stubs for the new API

API and Format

API Changes: Yes

• New public method: Table.append(row) accepting dict | list | tuple
• Blocking operation (releases GIL during execution)

Storage Format: No changes

Documentation

New Feature: Yes

• Added docstring with examples for dict, list, and tuple input
• Added type stubs in __init__.pyi
• Added usage examples in example/example.py

[fresh-borzoni]

@luoyuxia PTAL, when comfortable 🙏