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/protocol.rs

@@ -157,6 +157,8 @@ pub enum PluginRequest {
     SolidOperation { operation: crate::host::SolidOperation },
     /// V7 (additive): drawing table record create/modify/rename/delete.
     TableOperation { operation: crate::host::TableOperation },
+    /// V7 (additive): drive an OCS command.
+    RunCommand { request: crate::host::CommandRequest },
 }
 
 /// Responses the host sends back for `PluginRequest`.
@@ -192,6 +194,7 @@ pub enum PluginResponse {
     SelectionResult(Result<(), String>),
     SolidResult(Result<Handle, String>),
     TableResult(Result<Handle, String>),
+    CommandResult(Result<crate::host::CommandOutcome, String>),
 }
 
 /// Messages sent from the host to the plugin runner.