Llamacpp model provider documentation

[westonbrown]

Description

Added comprehensive documentation for the LlamaCppModel provider, enabling users to integrate llama.cpp servers with the Strands SDK for local model inference.

Type of Change

• New content addition
• Content update/revision
• Structure/organization improvement
• Typo/formatting fix
• Bug fix
• Other (please describe):

New content addition

Motivation and Context

The LlamaCppModel class was recently open to the SDK here user-facing documentation. This PR provides complete documentation to help users understand and utilize llama.cpp integration for running quantized models locally with advanced features like grammar constraints, multimodal support, and custom sampling parameters.

Areas Affected

• Added: /docs/user-guide/concepts/model-providers/llamacpp.md
• Modified: mkdocs.yml - Added llama.cpp to Model Providers navigation

Screenshots

N/A - Documentation only

Checklist

• I have read the CONTRIBUTING document
• My changes follow the project's documentation style
• I have tested the documentation locally using mkdocs serve
• Links in the documentation are valid and working
• Images/diagrams are properly sized and formatted
• All new and existing tests pass

Additional Notes

• Documentation follows the same structure and tone as existing model provider docs (Ollama, LiteLLM, etc.)
• Covers all llama.cpp-specific features including 20+ sampling parameters
• Provides configuration examples for different use cases (high quality, balanced, creative, speed-optimized)

[awsarron]

can we match one of our existing docs pages? https://strandsagents.com/latest/documentation/docs/user-guide/concepts/model-providers/openai/ uses different headings for example