fix(vertexai): add timeout parameter support to ChatVertexAI and VertexAI

[Tombiczek]

Description

Added timeout parameter support to ChatVertexAI and VertexAI classes to control API request timeouts.

Relevant issues

Fixes #1286

Type

🆕 New Feature
🐛 Bug Fix
✅ Test

Changes

• Added timeout parameter to ChatVertexAI and VertexAI
• Refactored timeout field to _VertexAICommon parent class (also used by ChatAnthropicVertex)
• Added integration tests for ChatVertexAI timeout (streaming and non-streaming modes)
• Added unit test for VertexAI timeout parameter pass-through
• Minor formatting change in test_anthropic_utils.py (auto-formatted by make format)

Testing

All new and existing tests pass:

• 2 new integration tests:

  • test_chat_vertexai_timeout_non_streaming() - verifies timeout in non-streaming mode
  • test_chat_vertexai_timeout_streaming() - verifies timeout in streaming mode

• 1 new unit test:

  • test_timeout_parameter() - verifies timeout parameter is passed to underlying client

Additionally:

• make format - passed
• make lint - passed
• make test - passed

Note

ChatAnthropicVertex already had timeout support (now inherited from _VertexAICommon). No new tests were added for this class to keep changes minimal per contribution guidelines.