Food truck intent improvements - User interactions

The current user interaction of the food truck intent returns the available nearby food trucks on the current day.

We can improve user interaction by allowing the users to filter by
* **time of the day** (`breakfast`, `lunch`, or `dinner`)
* **day of the week** (`Monday`, `Tuesday`, ...)
* **cluster location** (`Dewey Square`, `Copley Square`, ...)
* **favorite food truck** (`where is {FT name} today?`)

Start by locating the food truck intent entry point in the Python project and trace how nearby trucks are selected for the current day. Define how time of day, weekday, cluster location, and favorite-truck queries should map to the existing interaction. Done means each listed query form returns the matching food trucks, with tests covering the filters.

Written by the indexing model from the issue text.