Design: the spend tables use the design system's table, and spend-table/spend-totals leave §5d #3615

For: the design audit (#2678): one page at a time onto §5's components, so docs/DESIGN.md §5d only shrinks.

Done:

• [ ] The spend tables spend.ts draws on the board is drawn from §5's components (src/web/ui.ts helpers, §5 classes) in place of .spend-table .spend-totals, which src/web/pages/board.ts defines today.
• [ ] Those classes' rules are gone and their names leave the src/web/pages/board.ts bullet of docs/DESIGN.md §5d. bun scripts/design-lint.ts passes, and so does --update with a lower or equal baseline.
• [ ] The pull carries before/after screenshots in light and dark, at desktop and 390 px wide. Nothing a person reads or taps is lost.
• [ ] The page's existing tests pass. A test asserts the old class names are absent from the page's HTML.

Files: src/web/pages/board.ts, docs/DESIGN.md, the page's test. Risk: another page borrowing one of these classes. git grep each name first, and if one is used elsewhere, keep it and say so in the pull.

Parked by the crew: the check stayed red through 2 automatic tries (pull #3824 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 in the place it ran, not in the change, and failed the same way when it was run again (pull #3935 closed).

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

1. the check stayed red through 2 automatic tries (pull #3824 closed)
2. the check failed in the place it ran, not in the change, and failed the same way when it was run again (pull #3935 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.

Split into #3972 (.spend-table → plain §5 .table) and #3973 (.spend-totals → base.ts utilities, waits for #3972). Each is one small change on its own; the second park was the check failing where it ran, so both say to name that in the pull rather than rework the change.

Steward (trevato): pull #3935 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.