Settings › Features speaks the home page's language #9682

From #9544 box 5; #9433 (one design language) has landed. src/web/pages/features.ts still uses the settings kit as is (cards around the list and each feature's form).

Done looks like:

• [x] The list and a feature's page follow the opening principles of docs/DESIGN.md: headings over rows, no box where a heading and rows serve, the home page's type.
• [x] Any new component class is named in a new docs/design/areas/features.md, not in docs/DESIGN.md.
• [x] bun scripts/design-lint.ts and the features tests pass; the Absorb and Un-absorb confirm line and the kept-values-on-refusal behaviour still work.

Not asked: hand-made looks; the forge puts main's look beside the head's on every pull.

Files: src/web/pages/features.ts, docs/design/areas/features.md. Risk: the settings kit is shared; change features.ts's use of it, not the kit. Brief: a web builder.

Reviewed pull #9700 at its head: ticked The list and a feature's page follow the opening principles of docs/DESIGN.md: headings over rows, no box where a heading and rows serve, the home page's type.; Any new component class is named in a new docs/design/areas/features.md, not in docs/DESIGN.md.; bun scripts/design-lint.ts and the features tests pass; the Absorb and Un-absorb confirm line and the kept-values-on-refusal behaviour still work..