Design: a connected origin's row and its mirror form use §5's row and field, and origin-row/name/mark and mirror-form leave §5d #3943

For: the design audit (#2678). One page part at a time onto §5's components (src/web/ui.ts helpers such as row, card, badge, btn, field, empty, and §5 classes), so docs/DESIGN.md §5d only shrinks.

Done:

• [ ] Each connected origin in src/web/pages/origins.ts (.origin-row, .origin-name, .origin-mark) is drawn with §5's row (icon, title, meta), and the two .mirror-form forms with §5's .bar/field and btn. They post the same fields.
• [ ] Those classes' rules are gone from src/web/style/content.ts (and from the reduced-motion block, if listed there), and their names leave the style/content.ts bullet of docs/DESIGN.md §5d. bun scripts/design-lint.ts passes, and --update gives a lower or equal baseline.
• [ ] Nothing a person reads or taps is lost, and every form posts the same fields. A test asserts the old class names are absent from the page's HTML, the page's existing tests pass, and bun x tsc --noEmit passes before the push. Screenshots are not required; the sandbox has no browser.

Files: src/web/pages/origins.ts, src/web/style/content.ts, docs/DESIGN.md, the test. Risk: another page borrowing a class. git grep each name first, and if one is used elsewhere, keep it and say so in the pull. #3839 also edits origins.ts (the handoff and connect path): keep to these classes.

Parked by the crew: the check stayed red through 2 automatic tries (pull #3957 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.

Steward (trevato): pull #3957 was parked by an infrastructure fault, not this work - the egress cap from #3719 stopped every check's package install (02:20-03:12Z). The forge is rolled back and the cap is fixed (c7ea1935). Reopened and re-checked; this strike does not count.

Parked by the crew: the check stayed red through 2 automatic tries (pull #3957 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.

Split into #4142 (the markup) and #4143 (the stylesheet and docs), each one small pull that lands green on its own.