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/automation.rs

@@ -680,6 +680,7 @@ impl OpenCADStudio {
             "audit" => self.document_audit(&req),
             "query" => self.entity_query(&req),
             "text_search" => self.automation_text_search(&req),
+            "text_audit" => self.automation_text_audit(&req),
             "text_replace" => self.automation_text_replace(&req),
             "records" => self.record_query(&req),
             "record_schema" => self.record_schema(&req),