Update hip-1259.md to reflect acceptance by hedera (#1278)

Signed-off-by: Michael Garber <michael.garber@hashgraph.com>

Author: mgarbs

HIP/hip-1259.md

@@ -7,8 +7,10 @@ requested-by: Hashgraph
 type: Standards Track
 category: Core
 needs-hiero-approval: Yes
-needs-hedera-review: Yes
 status: Approved
+needs-hedera-review: Yes
+hedera-review-date: 2025-08-19
+hedera-acceptance-decision: Accepted
 created: 2025-07-11
 last-call-date-time: 2025-08-12
 discussions-to: https://github.com/hiero-ledger/hiero-improvement-proposals/pull/1259