Add support for Claude Opus 4.6

[sebsto]

This PR adds support for Anthropic's Claude Opus 4.6 model to the Bedrock service library.

Changes

• Added claude_opus_v4_6 model definition in AnthropicBedrockModels.swift
• Implemented Claude_Opus_v4_6 modality struct in AnthropicGlobalModels.swift with support for:
  • Text generation
  • Converse API (streaming and non-streaming)
  • Global cross-region inference
• Updated BedrockModel.swift to include the new model in the initialization logic

Model Specifications

• Model ID: anthropic.claude-opus-4-6-v1
• Max tokens: 128,000 (default: 8,192)
• Max prompt size: 200,000 tokens
• Max reasoning tokens: 8,191 (default: 4,096)
• Features: Text generation, system prompts, document processing, vision, tool use, reasoning

Technical Details

The implementation follows the existing pattern for Anthropic models, delegating to the AnthropicText helper for request/response handling while implementing the required modality protocols for Bedrock and Converse API compatibility.
Revert