docs(plans): record step 11a's and 11b's MRs in the S04-A Status table

Step 11 of the S04-A per-format credential columns plan ships as two merge requests, the un-bind then the drop, and the plan keeps one Status row for both. This records both halves, in merge order, using the same (<id>, <qualifier>) shape row 3 already uses for its own split:

• !2677 (merged) — 11a, the un-bind
• !2681 (merged) — 11b, the drop

Opened alongside them rather than from either, because a step MR does not edit the plan. This is the standing single writer for this plan's table while the workstream has steps in flight, which is what keeps parallel step MRs off adjacent rows.

Rows 4, 5, 7 and 8 are left empty. They belong to other steps' authors and sit on lines adjacent to this one, which is the collision the plan table's single-writer rule exists to avoid.