#28326 plans: log three sidebar commits that reached the base without a Sidebar-Look trailer (base red)

Fixes a base red that blocks every PR's cmux-next checks.

The sidebar owner sweep (cmux-next.yml, "Pushed commits add no violations", prepush-gate.py --only sidebar --commits 342462ca..HEAD) names three commits on the base branch that reached it without a Sidebar-Look: trailer:

• 4367c16e12c, from #24073 (the traffic-lights clip; its look is already logged under "Scrolled rows hide under the traffic lights" as f19e4c28604)
• 6c1a5ab8bf3, from #24295 (menu row grid; already logged and reviewed as 350b65e877c, SidebarFooterBand.swift only)
• eb8105b0747, from #27561 (trailing marks and controls on one column and one slot pitch)

Every PR whose merge includes them fails "Fail on any red check" with 3 commit(s) change the sidebar's drawing code without a Sidebar-Look: trailer or an entry in plans/cmux-next/sidebar-owner.md. This currently blocks about 15 reviewed PRs, among them #28320, the fix for the webviews check:fixed-waits base red.

sidebar_owner() passes a commit whose 11-character sha appears in plans/cmux-next/sidebar-owner.md ("a commit that reached the branch without a trailer ... is reviewed once instead of failing every later sweep"). This PR adds those three rows and nothing else.

Risk: docs-only, 3 added lines in one plans file. No code or workflow changes.

No capture: docs-only change to a plans file.

Agent session: agent session

🤖 Generated with Claude Code

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Summary by cubic

Fixes the sidebar owner sweep base red by logging three commits that reached the base branch without a Sidebar-Look: trailer. Each commit's look was already reviewed when its original change landed, so logging their shas in plans/cmux-next/sidebar-owner.md stops them from failing every later sweep. Docs-only, three added lines in one plans file.