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/client.rs

@@ -482,6 +482,18 @@ impl HostApi for PluginHostApi {
         }
     }
 
+    fn run_command(&mut self, request: crate::host::CommandRequest) -> Result<crate::host::CommandOutcome, String> {
+        match self.client.request(PluginRequest::RunCommand { request }) {
+            Ok(PluginResponse::CommandResult(result)) => {
+                self.document_cache = OnceCell::new();
+                result
+            }
+            Ok(PluginResponse::Error(error)) => Err(error),
+            Ok(other) => Err(format!("unexpected command response: {other:?}")),
+            Err(error) => Err(error.to_string()),
+        }
+    }
+
     fn table_operation(&mut self, operation: crate::host::TableOperation) -> Result<Handle, String> {
         match self.client.request(PluginRequest::TableOperation { operation }) {
             Ok(PluginResponse::TableResult(result)) => {