Organization catalog added; release feed filters updated

Added

• Browse every tracked organization on a new A-to-Z catalog page, reachable from the header nav.
• The home page now spotlights a curated set of featured organizations.
• Filter releases on an organization feed by time range — last 30 days, 3 months, year, or all time.
• Filter organizations by category in the MCP server's list_organizations tool.

Changed

• Aliased category links now resolve to the right category across the web app and MCP server.