feat(text): add text_audit spell-check and dry-run replacement simulation

- Adds 	ext_audit operation under ocs_read, control bridge, and headless server
- Implements pairs / dry_run_pairs simulation returning diffs, coordinates, and unmatched queries
- Implements check_terms suspect matching and dictionary vocabulary verification
- Adds dry_run: true to 	ext_replace to preview modifications without mutating entities or pushing undo
- Supports bounds, layers, handles, and scope filtering
- Updates MCP tool definitions, schemas, and automation test suites

src/app/control/mod.rs

@@ -472,6 +472,7 @@ impl OpenCADStudio {
                 | "get_selection"
                 | "audit"
                 | "text_search"
+                | "text_audit"
         );
         if !query && !self.control.enabled {
             return (
@@ -731,6 +732,7 @@ impl OpenCADStudio {
                 "xdata_get" => self.xdata_read(&req),
                 "get_selection" => self.control_get_selection(),
                 "text_search" => self.control_text_search(&req).unwrap_or_else(|e| e),
+                "text_audit" => self.control_text_audit(&req).unwrap_or_else(|e| e),
                 "history" => {
                     json!({"ok":true,"entries":self.command_line.history.iter().map(|e|json!({"kind":format!("{:?}",e.kind),"text":e.text})).collect::<Vec<_>>()})
                 }