- Add ResearchTools class in gitea/tools/research_tools.py
- web_search: DuckDuckGo HTML search, no API key required
- fetch_url: httpx-based URL fetcher with HTML stripping + truncation
- Wire both tools into planning_tools and coding_tools_list in dispatcher.py
- Add 19 unit tests covering all methods, error paths, and edge cases
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Co-authored-by: Michael <michael@example.com>
Reviewed-on: #2
