docs: ROADMAP Done table omits the #330 completion (PR #331) #332

Problem

The ROADMAP Done table does not record the #330 completion (PR #331).

Verified on main 34f47b5c1307f7268b52f42d1097ae4614505b95 (= origin/main HEAD, the PR #331 merge commit):

• grep -n "330\|331" ROADMAP.md returns no matches.
• The newest Done row is the docs(roadmap): record the #326 completion in Done (#328) #329 row (ROADMAP.md:78): ROADMAP Done records the #326 completion | 2026-10-23 | #329.
• Issue docs: ROADMAP Done table omits the #328 completion (PR #329) #330 ("docs: ROADMAP Done table omits the docs: ROADMAP Done table omits the #326 completion (PR #327) #328 completion (PR docs(roadmap): record the #326 completion in Done (#328) #329)") is CLOSED (2026-10-23T12:40:10Z) via PR docs(roadmap): record the #328 completion in Done (#330) #331 MERGED (2026-10-23T12:40:09Z, merge commit 34f47b5) — both verified with fresh gh calls this run.

This is the recurring one-step lag in the Done table: each ROADMAP-docs PR records the previous completion, so its own completion is left unrecorded until the next round (same pattern as #310/#314/#319/#322/#324/#326/#328/#330).

Fix

Add one row at the head of the Done table, aligned with the neighbouring rows:

| ROADMAP Done records the #328 completion                         | 2026-10-23 | #331     |

Leave the Sources line unchanged, per the PR #315/#318/#320/#323/#325/#329/#331 precedent.

Acceptance criteria

• ROADMAP.md Done table head carries the docs(roadmap): record the #328 completion in Done (#330) #331 row above, exactly one added row, column alignment matching the neighbouring rows.
• No other file changes.

Note: this issue's own completion (the PR that adds the row) will itself be missing from Done — that is the expected next round of this same pattern, not a defect in the fix.