* test(e2e): add golden tests for fresh terminal and shell commands
Adds regression tests for terminal initialization in fresh profiles and shell command execution to the golden test suite, integrated across Linux, macOS, and Windows CI.
* test(e2e): bracket shell command output between markers
The echoed command can wrap or be clipped by the buffer tail. Bracket output between begin and end markers to reliably identify real output, and strip ANSI escape sequences that interfere with parsing.
