docs(qa): the aggregate matrix's history row records the #24618 fix that landed on main

Claude-Session: https://claude.ai/code/session_01FM29ZqLTrnPNXxijioZwMp
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

docs/qa/platform-checklist/areas/api-backend.json

@@ -1921,7 +1921,7 @@
         {
           "revision": 3,
           "date": "2026-10-19",
-          "change": "steps[3], steps[5], knownGaps[1] and negative[2] name the doors that answer — checklist-accuracy findings of the 18.0 QA sweep (QA run #24541 step 6, and QA run #24595 knownGaps[1] / step 4 / negative[2], api-backend.aggregate-contract-matrix; wave anchor #24579 §3, comment 6272314386). On POST /data/:object/query a non-array aggregations is refused by the request schema before the protocol's worked example, and that door carries no timezone; the lever is POST /api/v1/analytics/query on cube showcase_delivery / due_date. negative[2] now says a date dimension's labels are zone-independent; that row's FAIL is the product defect #24618 (open), unchanged. Re-derived at base 9a7838edf5 (protocol.ts assertAggregationFieldsExist, objectql engine.ts ENGINE_AGGREGATE_OPTION_KEYS, spec data/analytics.zod.ts timezone, examples/app-showcase/src/data/analytics/showcase.cube.ts)",
+          "change": "steps[3], steps[5], knownGaps[1] and negative[2] name the doors that answer — checklist-accuracy findings of the 18.0 QA sweep (QA run #24541 step 6, and QA run #24595 knownGaps[1] / step 4 / negative[2], api-backend.aggregate-contract-matrix; wave anchor #24579 §3, comment 6272314386). On POST /data/:object/query a non-array aggregations is refused by the request schema before the protocol's worked example, and that door carries no timezone; the lever is POST /api/v1/analytics/query on cube showcase_delivery / due_date. negative[2] now says a date dimension's labels are zone-independent; that row's FAIL was the product defect #24618, which PR #24642 (787939130c) fixed on main after this round's base; the clause is unchanged. Re-derived at base 9a7838edf5 (protocol.ts assertAggregationFieldsExist, objectql engine.ts ENGINE_AGGREGATE_OPTION_KEYS, spec data/analytics.zod.ts timezone, examples/app-showcase/src/data/analytics/showcase.cube.ts)",
           "ref": "#PENDING-24579R3"
         }
       ]