fix(terminal): restore full PATH and consistent shell init for PTY sessions

[dtger]

Summary

• ensure PTY sessions on macOS inherit the user's full shell-derived PATH, including tools installed via Homebrew, bun, nvm, and similar setups
• start interactive PTY shells as login shells and run shell-wrapped PTY commands with -lc for more consistent environment initialization
• keep direct binary execution with command_args unchanged while reducing cases where commands work in an opened terminal but fail in a PTY-launched command

Problem

macOS GUI apps launched outside a terminal can inherit a minimal PATH, which caused PTY sessions to miss user-installed binaries. interactive PTY shells using login-shell behavior should also be aligned with shell-wrapped PTY commands.

Approach

• call ensure_macos_path() before spawning PTY processes so terminal sessions inherit the corrected process environment
• use -l for interactive Unix PTY shells
• use -lc for Unix shell-wrapped PTY commands to align command execution with interactive terminal environment setup

Notes

• this intentionally relies on the user's shell configuration to derive PATH on macOS, matching expected terminal behavior
• direct binary invocation via command_args remains the preferred path when exact argument handling is needed