[APP] Caesar

**Name of app / service**

Caesar (app slug `caesar`), a web search and page-reading API for AI agents.

**Link to developer documentation**

https://docs.trycaesar.com

**Is lack of support preventing you from moving forward, or do you have a workaround?**

It is a prerequisite. I opened component PR #21319 (Search Web and Get Document actions), and the maintainers noted the `caesar` app needs to exist in the registry before the components can be reviewed. This request is to register the app so that PR can proceed.

Auth model: Caesar requires an API key on every request. Users sign up at https://app.trycaesar.com, create a key, and send it as `Authorization: Bearer `. So the app should be configured with a **required** API key, not an optional one.

**Are there specific actions or triggers you'd like to see for this app?**

The two already in PR #21319: Search Web (ranked web search) and Get Document (read a page as clean markdown by URL or doc_id). Both are read-only.