feat: add Mistral AI provider, Firecrawl and SerpAPI tools

[mrbeandev]

Added new LLM provider:

• Mistral AI (https://api.mistral.ai/v1) Supports models: mistral-tiny, mistral-small, mistral-medium, etc.

Added new tools:

• firecrawl: Advanced web scraping with markdown extraction, screenshots, structured data extraction using LLM. Supports Firecrawl API.
• serp_api: Google search via SerpAPI with organic results, knowledge graph, related questions, and more.

Changes:

• pkg/config/config.go: Added Mistral provider config and tool configs
• pkg/providers/http_provider.go: Added Mistral routing and auto-detection
• pkg/agent/loop.go: Registered Firecrawl and SerpAPI tools
• pkg/tools/firecrawl.go: New tool implementation with tests
• pkg/tools/serpapi.go: New tool implementation with tests
• config/config.example.json: Added configuration examples
• pkg/providers/mistral_test.go: Integration test for Mistral provider

[yinwm]

Closure Notice

Thank you for this contribution! However, I'm closing this PR because it appears to be superseded by #246 (feat: Add Mistral AI provider support).

Reason

Both PRs add Mistral AI provider support:

• This PR (feat: add Mistral AI provider, Firecrawl and SerpAPI tools #193): Adds Mistral + Firecrawl + SerpAPI
• feat: Add Mistral AI provider support #246: Focused solely on Mistral provider

Since #246 is more focused and already under review, I recommend consolidating efforts there.

For the additional tools

The Firecrawl and SerpAPI tool integrations are valuable additions. I suggest:

1. Firecrawl: Please open a separate PR focused only on the Firecrawl tool
2. SerpAPI: Please open a separate PR focused only on the SerpAPI tool

This keeps provider additions and tool additions decoupled, which aligns better with the ongoing provider refactoring effort (#283).

Context

We are currently refactoring the provider architecture (Issue #283, Discussion #122). After Phase 2, adding new OpenAI-compatible providers like Mistral will be a simple configuration change rather than requiring code modifications.

Thank you for your understanding and contributions!