As an editor, I want to be able to mark external mismatches as exceptions to indicate that the Wikidata value is correct.

Entry points to toggle exceptions:

• API
• Special Page External Validation
• Common Special Page (when implemented, see T110039)
• Make feature accessible only for limited users (e.g., autoconfirmed group)

Exception table:

• Statement GUID of statement that caused the external mismatch as key
• [Maybe] additional information like the date it was introduced, ...

Displaying violations:

• Mismatches that were marked as exceptions should be displayed as one
• Need to check if a mismatch has an exception in the table
• Show exceptions in API result

[Maybe] renaming:

• "Exception" indicates that a rule was violated (like for constraints)
• Here, it indicates that the Wikidata value is correct
• If not internal, maybe rename it in the user interface for more clarity

For further information, marking mismatches as exceptions is implemented on the abandoned branch (old master branch): https://git.wikimedia.org/log/mediawiki%2Fextensions%2FWikibaseQualityExternalValidation/refs%2Fheads%2Fabandoned.