Merge lane Runs tab: follow-ups seen

Seen while doing the visual check for Task 7087 on the project's Merge lane › Runs tab. 1. A streak row (`×N`) should open to list the runs it stands for. Right now only the newest run links, and the others can't be reached from the tab. 2. The lane should file no run at all when the base is red and the queue hasn't changed since the last skip-only run. That stops the streak from growing in the first place, and it frees a slot each time. 3. The Merge column should be sortable (or at least filterable to runs that merged something), so the slowest gates can be compared without scrolling through the list. 4. The tab header says "Inactive — the lane needs a GitHub, GitLab or Azure DevOps repository" while it still lists past runs. It should say why the runs exist, or link to the repository setting that fixes it. Out of scope: the gate and the merge logic beyond item 2. Done means: - Each item is visible on the Runs tab (or in lane filing, for item 2) and covered by tests, or declined with a reason.

PR #5792 merged: Runs tab streak rows list their runs, Merge sorts, inactive header links its fix; lane files no run on an unchanged red queue (1h recheck, assumed). Quick gate + suites green; visual check done. Draft 7129 filed; deploy superseded.