feat(mcp): declarative op table and per-variant request validation

- Define Ty, Param, Rule, and OpDef in src/mcp_ops.rs for all 39 mutations
- Generate Draft 2020-12 schema using per-op anyOf variants with op enum discriminators
- Disambiguate colliding properties (replace, center, name) across mutation variants
- Add pre-dispatch validator enforcing required fields, rules, and parameter types
- Emit unknown parameter warnings into response warnings
- Introduce target_document_id for entities_copy_to with deprecated document_id fallback
- Update unit tests and automation smoke assertions

src/app/control/sheets.rs

@@ -231,8 +231,9 @@ impl OpenCADStudio {
         req: &Value,
     ) -> Result<Task<Message>, Value> {
         let handles = crate::app::control::entities::hex_handles(req, "handles")?;
-        let target = req["document_id"]
+        let target = req["target_document_id"]
             .as_u64()
+            .or_else(|| req["document_id"].as_u64())
             .ok_or_else(|| failure("document_required", "Supply the target document_id"))?;
         let source_index = self.active_tab;
         let target_index = self