feat(python): command runner and modify wrappers (doc.command, doc.modify)

HostApi::run_command drives the real OCS command through the same primitives
the automation channel uses, synchronously on the host thread: run a line,
start a command and answer point/text/token/entity/selection/enter prompts, or
cancel (closing anything the command opened). Refused while another command is
active, for a denylist (QUIT, NEW, OPEN, SAVE*, PY_* ...) and off the active tab.
Python: doc.command, doc.start_command and doc.modify (offset, trim, extend,
fillet, move, copy, rotate, scale, mirror, erase). Real-IPC audit checks exact
geometry for every wrapper plus guards and undo; IPC and Python unit tests; docs.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

src/app/control/mod.rs

@@ -314,7 +314,7 @@ fn command_selection_policy(name: &str) -> &'static str {
     }
 }
 
-fn active_command_metadata(command: &dyn crate::command::CadCommand) -> Value {
+pub(super) fn active_command_metadata(command: &dyn crate::command::CadCommand) -> Value {
     let options = command.options();
     let mut accepts = Vec::new();
     if command.is_selection_gathering() {