[idea] UI loop: apply directly with one check per batch, SCSS-first, lint regressions N1–N4

[MendixMau]

The idea: for the same ~3 h of UI work, the toolkit arm made 1,507 calls to the MCP arm's 515. The toolkit arm's result was closer to the wireframes. The extra calls came from two things:

• 7 drafting agents each ran check → exec → mx check → fidelity on every script, then the lead re-applied it.
• Round 1 introduced four regressions (N1 shell detached, N2 .d-none precedence, N3 32 px autoFit columns, N4 focus ring).

Proposals:

• UI agents apply directly, with one mx check per batch.
• Cross-cutting fixes first, done once as SCSS.
• Re-review only the pages that changed.
• Add N1–N4 as a pre-apply lint in check-page-shell.sh / learned-css-that-never-applied.md.

Field evidence: contrib/inbox/2026-09-29-ui-loop-efficiency.md (#165).

Done = the next UI round needs about half the calls, with no fidelity regression.