Design: the /boards data and pin forms draw their fields as §5 `.field`, not `.qf` #3906

Part of #3849 (design audit #2678), split after two pulls failed the check with src/web/pages/boards.ts(146,83): error TS2304: Cannot find name 'Html'. If you name the Html type, import it: import { html, raw, when, type Html } from "../html.ts"; Run bun x tsc --noEmit before the push.

Done:

• [ ] Every <label class="qf"><span>…</span>control</label> in src/web/pages/boards.ts becomes §5's field markup, <div class="field"><label for="ID">…</label>control</div>, with a unique id on each control so the label is tied to it. Every form posts the same field names as before.
• [ ] test/boards-selectors.test.ts matches the new markup in place of class="qf" (the old regex encodes the old class, so changing it is a test fix; say so in the pull), and one assertion checks class="qf" is absent from /boards/data's HTML.
• [ ] bun x tsc --noEmit, bun scripts/design-lint.ts and bun test test/boards pass.

Files: src/web/pages/boards.ts, test/boards-selectors.test.ts. Out of scope: boards-view.ts (its own issue) and the .qf CSS rules in src/web/style/content.ts and its §5d entry (removed after both). Screenshots are not required; the sandbox has no browser.

Parked by the crew: the check failed in the place it ran, not in the change, and failed the same way when it was run again (pull #3910 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.

Steward (trevato): pull #3910 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 failed ("the terminal on the website > the crew form picks a model from a list") and the decider saw no point in another try (pull #3910 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.

Parked by the crew: the check failed ("live triage where there is little to file under > at most 25 issues are filed per tick; the rest are missed, then filed") and the decider saw no point in another try (pull #4001 closed).

Parked twice since a person last spoke here, so it is the planner's now. Every reason:

1. the check failed ("the terminal on the website > the crew form picks a model from a list") and the decider saw no point in another try (pull #3910 closed)
2. the check failed ("live triage where there is little to file under > at most 25 issues are filed per tick; the rest are missed, then filed") and the decider saw no point in another try (pull #4001 closed)

The planner splits it, replaces it with a fresh issue, or defers it; a person can also say what to try. Nothing starts here until then, and the board lists it.

Replaced by #4590. Both tries went red on tests the change never touched (migrate-after, origins-reconnect, livetriage, snapshot-mirror, strangers, or an "(unnamed)" hook timeout); those are now planned as #4577–#4582. The fresh issue keeps the diff to the named files and says to run design-lint and lower the baseline in the same pull.