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 <noreply@anthropic.com>

crates/ocs_plugin_api/src/ipc/server.rs

@@ -111,5 +111,6 @@ pub fn handle_plugin_request(
         SetSelection { handles } => PluginResponse::SelectionResult(host.set_selection(&handles)),
         SolidOperation { operation } => PluginResponse::SolidResult(host.solid_operation(operation)),
         TableOperation { operation } => PluginResponse::TableResult(host.table_operation(operation)),
+        RunCommand { request } => PluginResponse::CommandResult(host.run_command(request)),
     }
 }