fix(hook): restore terminal title updates and new-tab CWD inheritance

[moukrea]

Summary

• Start inner shell as login shell (argv[0] = -bash): the PTY proxy was starting a non-login shell, so /etc/profile.d/*.sh was never sourced — breaking VTE terminal integration (__vte_prompt_command, __vte_osc7) which provides dynamic title updates and CWD tracking via OSC 0/7 escape sequences
• Remove hardcoded static title: the one-time \x1b]0;bash\x07 was the only title the terminal ever saw, since the inner shell lacked VTE integration to send dynamic updates
• Parse OSC 7 in relay loop: extract CWD from the inner shell's OSC 7 sequences and call set_current_dir on the proxy process, keeping /proc/<pid>/cwd current for terminal new-tab inheritance and snag cwd/snag ls
• Fix SHLVL: decrement before exec so the inner login shell increments back to the expected level (1 instead of 2)