Research init

[healeyb]

This PR adds research report support to the Aiera MCP server, introducing three new tools:

• find_research — Browse and discover research reports with filtering by author, provider, ticker, date range, sector, index, watchlist, and region/country.
• get_research — Retrieve full research report content, summary, and metadata by ID.
• search_research — Semantic (hybrid neural + keyword) search within research document chunks, with fallback to standard text-based search on timeout/failure. Follows the same post_filter pattern used by the
  existing transcript and filing search tools.