fix: address PR #68 review — remove ANTLR visitors, fix error handling, clean up docs

- Regenerate ANTLR parser with -no-visitor flag, removing 2649 lines of
  unused visitor code (mdlparser_base_visitor.go, mdlparser_visitor.go)
- Restore .interp and .tokens files that were accidentally deleted
- Fix opAttributeObjects silently discarding createAttributeObject errors
- Fix deepCloneTemplate errors ignored in 3 test sites
- Add warning logs in augmentFromMPK when clone/augment fails
- Remove Claude-specific design docs from docs/plans/

Addresses remaining items from @ako's second review on PR #68.

Author: engalar

docs/plans/2026-03-30-widget-docs-and-customwidget.md

@@ -5,6 +5,7 @@ package executor
 import (
 	"encoding/hex"
 	"fmt"
+	"log"
 	"regexp"
 	"strings"
 
@@ -338,10 +339,12 @@ func opAttributeObjects(obj bson.D, propTypeIDs map[string]pages.PropertyTypeIDE
 		objects = append(objects, int32(2)) // BSON array version marker
 
 		for _, attrPath := range ctx.AttributePaths {
-			attrObj, _ := ctx.pageBuilder.createAttributeObject(attrPath, entry.ObjectTypeID, nestedEntry.PropertyTypeID, nestedEntry.ValueTypeID)
-			if attrObj != nil {
-				objects = append(objects, attrObj)
+			attrObj, err := ctx.pageBuilder.createAttributeObject(attrPath, entry.ObjectTypeID, nestedEntry.PropertyTypeID, nestedEntry.ValueTypeID)
+			if err != nil {
+				log.Printf("warning: skipping attribute %s: %v", attrPath, err)
+				continue
 			}
+			objects = append(objects, attrObj)
 		}
 
 		result := make(bson.D, 0, len(val))

docs/plans/2026-03-30-widget-docs-generation-design.md

@@ -27,7 +27,7 @@ endif
 
 generate: check-antlr $(LEXER) $(PARSER)
 	@mkdir -p $(OUTPUT_DIR)
-	$(ANTLR4) -Dlanguage=Go -package $(PACKAGE) -o $(OUTPUT_DIR) $(LEXER) $(PARSER)
+	$(ANTLR4) -Dlanguage=Go -no-visitor -package $(PACKAGE) -o $(OUTPUT_DIR) $(LEXER) $(PARSER)
 	@echo "Generated Go parser in $(OUTPUT_DIR)/"
 
 clean: