Python SDK

[nisukapalli]

Implemented Python SDK – high-level wrapper over GraphLite FFI bindings.

Components:

• GraphLite: Database connection with factory pattern (classmethod open())
• Session: User context for query execution and transaction management
• Transaction: ACID transactions with context manager support (auto-rollback)
• QueryBuilder: Fluent API for constructing GQL queries with method chaining
• TypedResult: Type-safe result deserialization into Python dataclasses
• Error hierarchy: Comprehensive exception classes (ConnectionError, SessionError, QueryError, TransactionError, SerializationError)

Features:

• Clean Pythonic API following sqlite3 conventions
• Full type hints for IDE support
• Lazy imports to avoid circular dependencies (TYPE_CHECKING pattern)
• Context managers for automatic resource cleanup
• Comprehensive error handling with custom exception hierarchy

Examples:

• basic_usage.py: Demonstrates all core SDK features
• README.md: Complete documentation with API reference and examples

Architecture:
Application → Python SDK (this PR) → FFI Bindings (ctypes) → GraphLite Core (Rust)

[GajananCh]

Issue: #19