+ utilities: load the button lib on the dev page

[Lwrless]

Follow-up B out of #240, whose follow-up list read: "dev.ts is missing from 6 further libs (base, breadcrumb, button, checkbox, form-control, utilities)."

That list was wrong. A missing dev.ts is not a defect on its own — scripts/dev/config-server.ts:133-135 falls back to src/main.ts, so a lib's own styles always load. dev.ts matters only when a playground needs a demo dependency. Measured on the dev server:

lib	.btn on its dev page	verdict
base, breadcrumb, checkbox, form-control	0	nothing foreign to load — not a gap
button	109, styled	its own lib — not a gap
utilities	7, unstyled	real gap

Five of the six were phantom. This PR is the one that survives.

The defect

config-server.ts:145 skips the automatic @zui/utilities injection for utilities itself, and the lib had no dev.ts. So @zui/button never loaded, and the seven <button class="btn"> examples that README.md:11-16,31 uses to demonstrate state / active / selected / disabled rendered with a transparent background and no radius — exactly what those examples exist to show.

README.md:701-704 also carried a .blocks > .btn {padding: 0 0.75rem; height: 2rem} rule in its inline <style>, hand-faking the geometry. Those values are precisely what the real lib applies (btn.css:2 → -px-3, -h-[--btn-height]; vars.css:5 → --btn-height: 2rem), so it is a workaround, and it would fight --btn-height for any sized button.

After

example	height	background	radius	::before
btn	32px	rgb(241,245,249)	4px	0
btn active	32px	rgb(241,245,249)	4px	1
btn selected	32px	rgb(241,245,249)	4px	0.1
btn primary	32px	rgb(59,130,246)	4px	0
btn primary active	32px	rgb(59,130,246)	4px	1, overlay rgba(0,0,0,.1)
btn primary selected	32px	rgb(59,130,246)	4px	0.1, overlay rgba(255,255,255,.1)
btn [disabled]	32px	rgb(241,245,249)	4px	display: none, opacity .7, cursor not-allowed

Before: transparent background, radius 0, --btn-height unset. The state effect is painted on ::before (state.css), not the element background, which is where the active / selected distinction lives. 0 console errors.

Known cost: workspace dependency cycles

Declaring @zui/button closes a loop, because utilities is the base CSS layer button builds on. The workspace goes from 0 cycles to 3:

avatar <-> button <-> utilities
button <-> icons  <-> utilities
button <-> utilities

pnpm install now prints [WARN] There are cyclic workspace dependencies: lib/avatar, lib/utilities, lib/button on every run. Confirmed absent on dev_optimize before this change.

This was a deliberate choice. vite.shared.ts:66 aliases @zui/* to lib/* unconditionally, so dev.ts resolves @zui/button with or without the declaration — the page renders identically either way, measured. Declaring it keeps the manifest honest and matches label, form and table, which all declare @zui/button for exactly this purpose. All the edges are devDependencies.

Lockfile

Hand-patched with only the lib/utilities → @zui/button link (+3 lines), then pnpm install --frozen-lockfile, which accepted it with no drift. A bare pnpm install on this repo resolves unrelated floating ranges to newer versions — 35 packages are currently behind, several by a major.

Validation

pnpm check green (lint, typecheck, 9 test files / 60 tests, 4 skill tests). Dev page verified in Chromium.

Independent of #240 and of the other follow-ups — no file overlap.