feat(uix): --state-* state-layer token set + accordion pilot

First step of the state-archetype unification (the audit's Arq.8 / the plugin's #1
rec): collapse the ~168 bespoke hover idioms into a canonical MD3 state layer. Adds
--state-hover / --state-press / --state-selected to archetypes.css — a translucent
`currentColor` overlay (8% / 12% / 12%), the single source for NEUTRAL interaction
feedback. Per-variant accent hover (solid -> palette-solid-hover, soft -> element, …)
stays in the recipes; the state layer owns the neutral / ghost tier.

Pilot: accordion-trigger:hover now uses var(--state-hover) instead of its bespoke
--accordion-trigger-hover-bg. Verified (computed): the token resolves to an 8%
currentColor tint on a real trigger (`srgb 0.125 / 0.08`); the color-mix + currentColor
chain confirmed directly. (Visual screenshot blocked by a renderer-hang in the tooling;
hover it live to see the tint.)

Rollout pending a design call: accordion has a TRANSPARENT base so a `background` swap
works; FILLED surfaces need a layered overlay (not a bg replace). The other ~30
neutral-hover components + the recipe orphan cleanup (--*-hover-bg) follow.

src/uix/eidos/archetypes.css

@@ -20,6 +20,20 @@
  * unwrapped (a11y fallback; components override it with their own focus rule).
  */
 
+/* ── State layer (MD3) — canonical hover / press / selected feedback ─────────
+ * A translucent `currentColor` overlay: the single source for NEUTRAL interaction
+ * feedback, collapsing the per-component hover idioms (each recipe was hand-rolling
+ * its own `--x-hover-bg`; the audit counted ~168 such rules). Components apply it as
+ * a `background` on a transparent interactive surface, or as a layered overlay on a
+ * filled one. A theme retunes the strength by overriding these. Per-VARIANT accent
+ * hover (solid → palette-solid-hover, soft → element, …) stays in the recipes — the
+ * state layer owns the neutral / ghost tier, not the valenced palette swaps. */
+:root {
+	--state-hover: color-mix(in srgb, currentColor 8%, transparent);
+	--state-press: color-mix(in srgb, currentColor 12%, transparent);
+	--state-selected: color-mix(in srgb, currentColor 12%, transparent);
+}
+
 /* ── Trigger ───────────────────────────────────────────────────────────────
  * Applies to anything that the user clicks/taps to activate or open.
  */

src/uix/eidos/components/accordion/accordion.css

@@ -149,8 +149,10 @@
 	font-size: var(--accordion-trigger-font-size-full);
 }
 
+/* Hover uses the canonical state layer (archetypes.css) instead of a bespoke
+ * `--accordion-trigger-hover-bg` — pilot of the `--state-*` unification. */
 [data-accordion-trigger]:hover {
-	background: var(--accordion-trigger-hover-bg);
+	background: var(--state-hover);
 	color: var(--accordion-trigger-hover-color);
 }