Fix OKHManifest.from_dict crashing on string items in list fields

Two list fields accepted strings in practice but the parser called
.get() on each item unconditionally, raising AttributeError and
producing an unactionable "Failed to parse content as OKHManifest:
'str' object has no attribute 'get'" error in both validate and fix.

making_instructions / design_files / manufacturing_files etc.:
  A plain string (e.g. an instruction step like "Heat oven to 350°F")
  is now coerced into a DocumentRef(title=<string>, path="", type=<field type>).
  The default doc type is now field-specific (making-instructions,
  operating-instructions, etc.) rather than always falling back to
  design-files.

standards_used:
  A plain string (e.g. "CC0-1.0") is coerced into
  Standard(standard_title=<string>).

Both cases now also raise a clear ValueError naming the offending
field and received type when an item is neither str nor dict.

materials already handled strings; this brings the other list fields
in line with that pattern.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: MakerNetwork

src/core/models/okh.py

@@ -833,26 +833,40 @@ def from_dict(cls, data: Dict) -> "OKHManifest":
             )
 
         # Handle document references
-        for doc_field in [
-            "manufacturing_files",
-            "design_files",
-            "making_instructions",
-            "operating_instructions",
-            "technical_specifications",
-            "publications",
-        ]:
+        _FIELD_DOC_TYPE = {
+            "manufacturing_files": DocumentationType.MANUFACTURING_FILES,
+            "design_files": DocumentationType.DESIGN_FILES,
+            "making_instructions": DocumentationType.MAKING_INSTRUCTIONS,
+            "operating_instructions": DocumentationType.OPERATING_INSTRUCTIONS,
+            "technical_specifications": DocumentationType.TECHNICAL_SPECIFICATIONS,
+            "publications": DocumentationType.PUBLICATIONS,
+        }
+        for doc_field in _FIELD_DOC_TYPE:
             if doc_field in data and data[doc_field] is not None:
                 doc_list = []
                 for doc_data in data[doc_field]:
-                    doc_type = DocumentationType(
-                        doc_data.get("type", DocumentationType.DESIGN_FILES.value)
-                    )
-                    doc = DocumentRef(
-                        title=doc_data.get("title", ""),
-                        path=doc_data.get("path", ""),
-                        type=doc_type,
-                        metadata=doc_data.get("metadata", {}),
-                    )
+                    if isinstance(doc_data, str):
+                        # Plain string (e.g. an instruction step) → title with no file path
+                        doc = DocumentRef(
+                            title=doc_data,
+                            path="",
+                            type=_FIELD_DOC_TYPE[doc_field],
+                        )
+                    elif isinstance(doc_data, dict):
+                        doc_type = DocumentationType(
+                            doc_data.get("type", _FIELD_DOC_TYPE[doc_field].value)
+                        )
+                        doc = DocumentRef(
+                            title=doc_data.get("title", ""),
+                            path=doc_data.get("path", ""),
+                            type=doc_type,
+                            metadata=doc_data.get("metadata", {}),
+                        )
+                    else:
+                        raise ValueError(
+                            f"'{doc_field}' items must be a string or dict, "
+                            f"got {type(doc_data).__name__!r}"
+                        )
                     doc_list.append(doc)
                 setattr(instance, doc_field, doc_list)
 
@@ -955,12 +969,21 @@ def from_dict(cls, data: Dict) -> "OKHManifest":
         if "standards_used" in data and data["standards_used"] is not None:
             instance.standards_used = []
             for std_data in data["standards_used"]:
-                std = Standard(
-                    standard_title=std_data.get("standard_title", ""),
-                    publisher=std_data.get("publisher"),
-                    reference=std_data.get("reference"),
-                    certifications=std_data.get("certifications", []),
-                )
+                if isinstance(std_data, str):
+                    # Plain string (e.g. "CC0-1.0") → standard title
+                    std = Standard(standard_title=std_data)
+                elif isinstance(std_data, dict):
+                    std = Standard(
+                        standard_title=std_data.get("standard_title", ""),
+                        publisher=std_data.get("publisher"),
+                        reference=std_data.get("reference"),
+                        certifications=std_data.get("certifications", []),
+                    )
+                else:
+                    raise ValueError(
+                        f"'standards_used' items must be a string or dict, "
+                        f"got {type(std_data).__name__!r}"
+                    )
                 instance.standards_used.append(std)
 
         # Handle software