Fix #4612: Return non-zero exit code when CLI session ends with error

[jalateras]

Summary

This PR fixes the CLI to properly return a non-zero exit code (1) when a session ends with an error, allowing scripts and CI/CD pipelines to detect failures.

Problem

When the goose CLI encounters an error during a session (such as an invalid temperature parameter), it prints the error message to stderr but still exits with code 0. This makes it impossible for automated scripts to detect when goose has failed.

Solution

Added std::process::exit(1) after printing the error message when a session fails. This ensures the process exits with a non-zero status code that scripts can detect.

Changes

• Modified crates/goose-cli/src/cli.rs to call std::process::exit(1) when session.interactive() returns an error

Testing

• Built the project with cargo build --package goose-cli
• Ran existing tests with cargo test --package goose-cli
• Verified clippy passes with no warnings
• Manual testing confirms:
  • Normal sessions still exit with code 0
  • Error conditions now exit with code 1

Example

Before this fix:

$ GOOSE_TEMPERATURE="0.3" goose <<< "hey"
Session ended with error: ...
$ echo $?
0  # Wrong - should be non-zero

After this fix:

$ GOOSE_TEMPERATURE="0.3" goose <<< "hey"
Session ended with error: ...
$ echo $?
1  # Correct - non-zero exit code indicates failure

Fixes #4612