Feat/refactor tools system

[lxowalle]

📝 Description

📝 Objective

Optimize the tools module to make developing and using tools more convenient.

📋 To-Do List

• Organize the project structure of the tools module, with each tool implemented in a separate file to ensure a clear structure. For instance, the current edit.go implements both the append_file and edit_file tools.
• Decouple the tools module. For example:Initializing tools will requires modifying the agent's code.
• Implement constraints for the tool interface. Currently, tools do not explicitly require users to implement methods like Name() and Description().
• Add configuration to enable/disable tools, disable some infrequently used tools by default
• Support a plugin system to enable hot-loading of tools (this feature may be implemented in another issue).feat(hooks/plugin): add lifecycle hooks + phase-1 plugin contract #473

🔗 Related Issues / PRs

• Fixes #
  [Feature] Add tools/tool_choice controller #627
• Relates to #
  feat: add HTTP proxy support for web tools #587
  feat(observability): add ToolObserver hook for structured tool tracing #490
  fix(security): Symlink TOCTOU race condition #482
  fix(security): workspace sandbox avoid time-of-check/time-of-use (TOCTOU) races #464
  fix(tools): add proxy support to web_fetch HTTP transport #447
  Added Email Tool, Calender Integration and System Stats Overview Tool #339
  feat: integrate Tavily search #340
  fix(security): harden sandbox — shell escape bypass, symlink TOCTOU, SSRF, working_dir validation #331
  feat: add browser automation tool via agent-browser CLI #318
  feat: add browser tool powered by playwright-go #187
  feat: Add mcp tools support #282

🗣️ Type of Change

• 🐞 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 📖 Documentation update
• ⚡ Code refactoring (no functional changes, no api changes)

🤖 AI Code Generation

• 🤖 Fully AI-generated (100% AI, 0% Human)
• 🛠️ Mostly AI-generated (AI draft, Human verified/modified)
• 👨‍💻 Mostly Human-written (Human lead, AI assisted or none)

📸 Evidence (Optional)

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☑️ Checklist

• My code/docs follow the style of this project.
• I have performed a self-review of my own changes.
• I have updated the documentation accordingly.