feat: add timeout support for stream operations

[omkute10]

Description

This PR adds timeout support for both synchronous and asynchronous stream operations in the Hyperspell Python SDK. The changes ensure that long-running streams don't hang indefinitely by allowing users to set a maximum duration for stream operations.

Key Changes:

• Added timeout parameter to Stream and AsyncStream constructors
• Implemented timeout logic for both sync and async stream iterations
• Added proper error handling for timeout scenarios
• Improved resource cleanup in context managers
• Added comprehensive docstrings and type hints

Usage Example:

# Synchronous stream with 30-second timeout
with client.resources.completions.create(
    messages=[...],
    stream=True,
    timeout=30.0  # Timeout in seconds
) as stream:
    for chunk in stream:
        print(chunk)

# Asynchronous stream with 60-second timeout
async with await client.resources.completions.acreate(
    messages=[...],
    stream=True,
    timeout=60.0  # Timeout in seconds
) as stream:
    async for chunk in stream:
        print(chunk)