feat: add Tavily as optional search provider for GeeksforGeeks in SmartWebSearcher

[mani2001]

Summary

• Added Tavily as a configurable alternative to Google HTML scraping for GeeksforGeeks code searches in SmartWebSearcher
• When TAVILY_API_KEY is set (via config.yaml or environment variable), Tavily's search() API with include_domains=["geeksforgeeks.org"] is used instead of fragile Google scraping
• Existing Google scraping path is preserved as fallback when Tavily is not configured or when a Tavily request fails

Files changed

• models/smart_web_searcher.py — Added Tavily client initialization, _search_geeksforgeeks_tavily() method, and routing logic to prefer Tavily when available
• requirements.txt — Added tavily-python>=0.5.0
• config.yaml — Added tavily.api_key configuration entry

Dependency changes

• Added tavily-python>=0.5.0 to requirements.txt

Environment variable changes

• Added TAVILY_API_KEY — read from config.yaml (tavily.api_key) or directly from environment

Notes for reviewers

• This is an additive change: the existing Google scraping path is fully preserved and used when Tavily is not configured
• GitHub and Stack Overflow searches are unchanged (they use official APIs)
• The Tavily method uses search_depth="advanced" for highest relevance and include_domains to scope results to geeksforgeeks.org
• run_in_executor is used to call the synchronous TavilyClient.search() from async context without blocking the event loop

🤖 Generated with Claude Code

Automated Review

• Passed after 2 attempt(s)
• Final review: All three fixes from attempt 2 are correctly applied and verifiable in the diff. (1) include_raw_content=True is present in the Tavily search() call, enabling the BeautifulSoup code-extraction path. (2) import os is placed alphabetically within the stdlib block (between json and re), satisfying PEP 8. (3) No GITHUB_TOKEN env-var resolution was added — the change stays in scope. The additive migration preserves the original _search_geeksforgeeks scraper as a fallback, tavily-python>=0.5.0 is added to requirements.txt, and TAVILY_API_KEY is documented in config.yaml. Tavily SDK call parameters (search_depth, include_domains, include_raw_content, max_results) are all valid. No broken imports, dead code, or unrelated changes detected.