Folder Trust & Security Review Flags

### What problem does this solve?
Allowing an AI agent arbitrary access to the entire file system is a security risk. Users need to be protected from accidental data modification in sensitive directories.

### How does this work?

We are implementing a "Folder Trust" system. When the CLI is initialized in a new directory, it will prompt the user to explicitly "trust" that workspace. This gives you control over which projects can use the full capabilities of the Gemini CLI. It prevents potentially malicious code from running by asking you to approve a folder before the CLI loads any project-specific configurations from it.