Phase 3 headline feature: everything falls out of SX's first-class env chain.
- make-tcl-interp extended with :frame-stack and :procs fields
- proc: user-defined commands with param binding, rest args, isolated scope
- uplevel: run script in ancestor frame with correct frame propagation
- upvar: alias local name to remote frame variable (get/set follow alias)
- global/variable: sugar for upvar #0
- info: level, vars, locals, globals, commands, procs, args, body
- tcl-call-proc propagates updated frames back to caller after proc returns
- test.sh timeout bumped to 90s for larger runtime
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
