Summary

• Document list filter parses Extended JSON (\$oid, \$date) instead of plain json.decode.
• A 24-character hex _id is wrapped as ObjectId.
• If _id is still a string and find returns nothing, the empty state explains how to write { \"_id\": { \"\$oid\": \"…\" } }.

Test plan

• Filter {\"_id\": \"<24-hex>\"} returns the document (not empty).
• Filter {\"_id\": {\"\$oid\": \"<24-hex>\"}} matches.
• Filter {\"created\": {\"\$date\": \"2024-01-15T12:30:00.000Z\"}} matches a DateTime field.
• Filter {\"_id\": \"not-an-objectid\"} with no hits shows the ObjectId hint.

Closes #783