feat: enhance agent functionality and add new tools

- Updated access control enforcement in tools and workflows to use `RequestContext` and agent-specific runtime context types.
- Added optional fields `userId` and `researchPhase` to `ResearchRuntimeContext` for improved context handling.
- Imported new agents: `calendarAgent`, `bgColorAgent`, and `danePackagePublisher` into the main index.
- Implemented a new tool `colorChangeTool` to change the background color with a defined input schema.