feat(ui-core): the design system moves to the b2iH preset

[YaelAnaya]

The design system moves from b3bXyyPdWj to b2iH, with --pointer on.

Stacked on #777 (the icon swap) and should merge after it — b2iH decodes
iconLibrary: lucide, which that branch already applied, so the two agree instead
of fighting.

What the preset actually changes

Decoded with shadcn preset decode b2iH, against the preset it replaces:

font         inter   ->  geist
fontHeading  geist   ->  inherit
chartColor   orange  ->  neutral
iconLibrary  tabler  ->  lucide     (already the product's, via #777)

style, base, baseColor, theme, radius, menuAccent, menuColor   unchanged

The values are the CLI's own output. shadcn@latest — 4.19.0, checked rather than
assumed — scaffolded the preset into a throwaway container and the delta was applied
from what it generated, which is how the previous preset's values got in too.

init was not run against this repository

The command as given scaffolds. --template react-router creates a react-router
project, and init rewrites components.json and the stylesheet wholesale — in a
workspace that already is a react-router app with a stylesheet carrying nine
justified extension tokens, that is not a configuration change but a replacement.
So the preset was generated in /tmp inside a container, and this branch carries
the difference between what it produced and what the repository had.

One family

--font-sans is Geist and --font-heading is var(--font-sans), so a heading is
the same face at a different size and weight rather than a second typeface.

The h1–h4 rule stays in the base layer even though it now changes nothing. It
keeps the semantic hook, so a later preset that splits the families again lands in
one declaration rather than at every heading — and the styleguide's browser check
still asserts each hook by name rather than against the other, because a heading
that had fallen back to the browser's default would satisfy "the two agree" while
proving the hook was never wired.

@fontsource-variable/inter is gone. The lockfile is resolved from the manifests
and a frozen install runs from an empty tree.

The chart palette, and what the trade is

Five neutral steps, identical in both themes as the orange ones were:

chart-1  oklch(0.87 0 0)     chart-4  oklch(0.371 0 0)
chart-2  oklch(0.556 0 0)    chart-5  oklch(0.269 0 0)
chart-3  oklch(0.439 0 0)

They separate by lightness rather than hue. That reads for somebody who cannot
separate two hues and it survives greyscale, at the cost of holding fewer series
apart before the steps run together. DESIGN.md says so, because a palette that
reads in greyscale and a palette that holds many series apart are not the same
palette, and the next person choosing between them should not have to work it out
from five oklch values.

Nothing in the product draws charts yet. The only surface using those tokens is
the styleguide's swatch row. So this change is real in the tokens and currently
invisible in the app — worth knowing before reading the baselines and wondering
where the colour went.

The pointer option

button:not(:disabled), [role="button"]:not(:disabled) { cursor: pointer; }

Scoped to what is pressable and stopped at :not(:disabled): a hand over a control
that will not respond is the cursor making a promise the control does not keep.

Test plan

Every command ran inside Docker/Linux; no repository validation ran natively on the
host.

install (pnpm install --frozen-lockfile, from an empty tree)  PASS
build (pnpm -r build)                                         PASS
@visionset/ui-core lint (incl. typecheck)                     PASS
@visionset/ui-core test                                       PASS
@visionset/app build                                          PASS
@visionset/app lint (incl. typecheck:e2e)                     PASS
@visionset/annotator test                                     PASS
pnpm test:scripts                                             PASS
pnpm version:check                                            PASS

full browser suite (all projects)                             276 passed
visual project, three consecutive runs                        10 / 10 / 10

Two gates caught the change before anything else did, which is what they are for:
tokens.test.ts on the chart values, the font pair and the import count, and the
styleguide's base-layer check on the two font hooks. Both were updated to the new
contract rather than relaxed.

The ten baselines were regenerated, opened and read. All of them carry type, so a
change of family moves all of them.

Scope

Routes changed:            No
Product IA changed:        No
Backend / wire / domain:   No
Primitive API changed:     No
Annotator behaviour:       No

Tokens and typography change; nothing about what the product does changes.

Note for merging

components.json and the preset agree again on every property. The divergence
#777 had to document — configuration saying lucide while the preset decoded
tabler — is gone, and the note describing it is removed rather than left to
describe a state that no longer exists.