Add tool execution delegate

[mattt]

Alternative to #108

[Copilot]

Pull request overview

This pull request introduces a ToolExecutionDelegate protocol that allows observing and controlling tool execution in language model sessions. It provides an alternative to PR #107's provider-specific approach by implementing a universal delegate pattern that works across all model providers.

Changes:

• Adds ToolExecutionDelegate protocol with methods to observe and control tool execution lifecycle
• Implements ToolExecutionDecision enum supporting .execute, .stop, and .provideOutput decisions
• Integrates delegate hooks into all model implementations (OpenAI, Ollama, MLX, Gemini, Anthropic)

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
Sources/AnyLanguageModel/LanguageModelSession.swift	Defines the ToolExecutionDelegate protocol, ToolExecutionDecision enum, and adds toolExecutionDelegate property to LanguageModelSession
Sources/AnyLanguageModel/Models/OpenAILanguageModel.swift	Integrates delegate hooks into tool resolution logic for both streaming and non-streaming responses
Sources/AnyLanguageModel/Models/OllamaLanguageModel.swift	Integrates delegate hooks into tool resolution logic
Sources/AnyLanguageModel/Models/MLXLanguageModel.swift	Integrates delegate hooks into tool resolution logic
Sources/AnyLanguageModel/Models/GeminiLanguageModel.swift	Integrates delegate hooks into tool resolution logic
Sources/AnyLanguageModel/Models/AnthropicLanguageModel.swift	Integrates delegate hooks into tool resolution logic
Tests/AnyLanguageModelTests/ToolExecutionDelegateTests.swift	Adds comprehensive tests for all three decision types (.stop, .provideOutput, .execute)
README.md	Documents the new delegate pattern with a practical example

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[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 6 comments.

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[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated no new comments.

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[Copilot]

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

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