Add json-pointer format to statementPointerTarget

[StephenAbbott]

Summary

Fixes #707.

The statementPointerTarget property on the Annotation object is described as an RFC6901 JSON Pointer but the schema only constrained it to type: string. This adds "format": "json-pointer" so validators reject values that are not well-formed pointers (e.g. missing leading / or containing invalid ~ escapes).

Change in schema/statement.json:

         "statementPointerTarget": {
           "title": "Statement Fragment Pointer",
           "description": "An RFC6901 JSON Pointer ...",
-          "type": "string"
+          "type": "string",
+          "format": "json-pointer"
         },

Test plan

• Added tests/data/invalid-statements/statement_annotations_statementPointerTarget_format.json with an invalid pointer (missing leading /)
• Added matching row to tests/data/invalid-statements/expected_errors.csv
• pytest tests/test_data.py — new test passes; no new failures (pre-existing 12 format-related failures on main in the local sandbox are environmental and unchanged here)
• All existing valid fixtures use well-formed pointers ("", /recordDetails/..., /statementDate) so none break under the new constraint

https://claude.ai/code/session_019ksAaAodXk1wNCLcuEVkXC

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Generated by Claude Code

[kd-ods]

Thanks, @StephenAbbott . This edit will require some work our end so I'll tag it as a good PR to start with if there's a future round of development on the schema.