Align shadcn's accent token with what shadcn means by it

shadcn uses `bg-accent` for its SUBTLE surfaces — dropdown item hover, command
row selection, ghost and outline button hover, the dialog close affordance. The
brand colour in shadcn is `primary`.

PIG's Tailwind config mapped `accent` to `--accent`, which is the brand. That
inverted the meaning, so every shadcn hover and selection state painted a
full-strength brand block. With the monochrome "pig" palette in dark mode the
brand is near-white, so a selected command row rendered as a white slab against
a near-black sheet. Measured before the change: selected row rgb(250,250,250)
on a rgb(9,9,11) body.

`accent` now aliases `--accent-subtle` and `accent-foreground` aliases
`--accent-fg`, which is what those tokens were created for. The eleven places
where PIG's own components wanted a solid brand fill — filled chips, selected
card borders, progress bars — move to `primary`, which still resolves to
`--accent`. A `brand` alias is added for clarity.

After: selected row rgb(39,39,42) in dark and rgb(244,244,245) in light, both a
subtle tint above the body; the pipeline's active stage chip stays a solid
rgb(250,250,250) fill, unchanged.

Found by opening overlays, which earlier screenshot sweeps never did — every
route had been checked, but a dropdown or a command palette only misbehaves
once it is open. Worth remembering: page-level sweeps do not exercise portals.

Typecheck clean, 135 unit tests and e2e green, CSP hash unchanged, 0px
horizontal overflow across 12 routes at 393px and 1440px.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

apps/web/tailwind.config.js

@@ -20,8 +20,22 @@ export default {
         foreground: 'hsl(var(--fg))',
         muted: 'hsl(var(--muted))',
         'muted-foreground': 'hsl(var(--muted))',
-        accent: 'hsl(var(--accent))',
-        'accent-foreground': 'hsl(var(--accent-on))',
+        /*
+         * shadcn's `accent` is its SUBTLE hover/selected surface — dropdown
+         * items, command rows, ghost-button hover. It is not the brand colour;
+         * that is `primary`, mapped below.
+         *
+         * Mapping `accent` to --accent (the brand) inverted this, so every
+         * hover state painted a full-strength brand block: in dark mode with
+         * the monochrome "pig" accent that is near-white, which made a selected
+         * command row glare. Aliased to the subtle pair instead, so shadcn
+         * primitives tint the way their authors intended while PIG's own brand
+         * fills use `primary`.
+         */
+        accent: 'hsl(var(--accent-subtle))',
+        'accent-foreground': 'hsl(var(--accent-fg))',
+        /** The brand itself, for PIG's own components that need a solid fill. */
+        brand: 'hsl(var(--accent))',
         'accent-fg': 'hsl(var(--accent-fg))',
         'accent-on': 'hsl(var(--accent-on))',
         'accent-subtle': 'hsl(var(--accent-subtle))',