docs(plans): record !2349 in the S04-A per-format columns Status table

Summary

Records !2349 (merged) against step 1 in the Status table of the per-format encrypted credential columns plan.

Step MRs do not edit the plan file, because parallel steps editing adjacent rows collide, so the table gets a single writer. This is that writer for this plan while its steps are in flight: the remaining rows land here as their MRs open.

Rows 2 to 11 are still empty, which means "not yet recorded", not "not started".

Governing ADRs

None. This edits one table cell in a plan document and touches no code, schema, or interface.

Testing

No test applies. markdownlint-cli2, vale and lychee run on the changed file in the pipeline.