feat(eidos): drag pickup-lift as a global motion token (--motion-scale-lift)

A grabbed surface scales slightly toward the viewer (depth 'picked up' cue). This
is a cross-component primitive, not a float-panel literal:

- New --motion-scale-lift (1.02) in STATIC_MOTION.scale + MOTION_SCALE_KEYS (the
  only >1 in the scale family); validated by validateEidosConfig.
- FloatPanel consumes it: [data-float-panel-content][data-dragging] { scale:
  var(--motion-scale-lift) } + will-change: translate, scale, eased lift/settle,
  static during the move (composited), suppressed under reduced-motion.
- Documented in eidos-motion.md §11 (primitives table) and THEMING.md §14 (new
  'Superficies arrastrables: el lift de pickup' pattern) so any draggable surface
  (slider thumb, sortable item, drawer) reuses the SAME token, not its own literal.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/uix/eidos/THEMING.md

@@ -1358,6 +1358,44 @@ Añade al recipe del componente si:
 - Es específico (un slider drag, una calendar swap).
 - No reacciona a una señal de sema, sino a un `data-state` transition.
 
+### Superficies arrastrables: el lift de "pickup"
+
+Cuando el usuario **agarra y arrastra** una superficie, ésta debe **subir hacia
+él** (profundidad: "lo he cogido"). Es un cue transversal — NO específico de un
+componente — así que el factor de escala es un **token global de motion**, no un
+literal por recipe:
+
+| Token | Valor | Uso |
+|---|---|---|
+| `--motion-scale-lift` | `1.02` | escala de pickup al arrastrar (el único `>1` de la familia `--motion-scale-*`) |
+
+**Patrón (cualquier draggable lo aplica igual)** — gateado por el data-attr de
+arrastre que su morfo declara (`data-dragging`, `data-grabbed`, …), emparejado
+con una elevación de sombra, y suprimido bajo reduced-motion:
+
+```css
+/* float-panel, un thumb de slider arrastrándose, un item sortable, un drawer… */
+[data-x][data-dragging] {
+  scale: var(--motion-scale-lift);   /* sube hacia el usuario */
+  box-shadow: var(--…-shadow-active); /* + eleva la sombra */
+}
+@media (prefers-reduced-motion: reduce) {
+  [data-x][data-dragging] { scale: 1; transition: none; }
+}
+```
+
+Reglas:
+- **`scale` (no `transform`)** para componer con la posición, que viaja por
+  `translate` (propiedades distintas) → el lift no pelea con el arrastre 1:1.
+- El cambio de `scale` se **transiciona** (lift al agarrar / settle al soltar);
+  durante el move queda **estático** (compuesto, sin coste por frame).
+- `will-change: translate, scale` mientras dura el gesto.
+- Un theme retematiza el lift en `STATIC_MOTION.scale.lift` (`primitives/static.ts`)
+  — todos los draggables lo heredan. No redefinir el 1.02 por componente.
+
+Hoy lo consume `float-panel` (`[data-float-panel-content][data-dragging]`); un
+slider/sortable que añada arrastre debe leer el MISMO token, no inventar el suyo.
+
 ---
 
 ## 15. Comparación con librerías de referencia

src/uix/eidos/components/float-panel/float-panel.css

@@ -26,10 +26,13 @@
 	font-size: var(--float-panel-font-size);
 	line-height: var(--float-panel-line-height);
 	box-shadow: var(--float-panel-shadow);
-	/* Only the elevation lift (→ topmost) is eased here. Position (`translate`)
-	   is never transitioned so the drag stays 1:1; presence is the preset's job. */
-	transition: box-shadow var(--float-panel-transition-duration)
-		var(--float-panel-transition-ease);
+	/* The elevation lift (→ topmost) AND the drag pickup-scale are eased here.
+	   Position (`translate`) is never transitioned so the drag stays 1:1; presence
+	   (scale on `[data-state]`) is the motion preset's job — distinct from this
+	   steady-state `scale` transition, which only fires on the grab/settle. */
+	transition:
+		box-shadow var(--float-panel-transition-duration) var(--float-panel-transition-ease),
+		scale var(--float-panel-transition-duration) var(--float-panel-transition-ease);
 }
 
 /* The focused/frontmost panel lifts. */
@@ -51,6 +54,15 @@
 	box-shadow: var(--float-panel-shadow-active);
 }
 
+/* Dragging also lifts the surface TOWARD the user (a subtle scale) — the depth
+   "pickup" cue paired with the elevation shadow. Move only: resize changes the
+   real size, so scaling it too would read wrong. `scale` composes with the drag
+   `translate` (distinct properties), is static during the move (composited, no
+   per-frame cost), and eases in on grab / out on settle via the base transition. */
+[data-float-panel-content][data-dragging] {
+	scale: var(--motion-scale-lift);
+}
+
 [data-float-panel-content]:focus-visible {
 	outline: none;
 	box-shadow:
@@ -323,4 +335,17 @@
 
 /* Reduced-motion for the open/close is handled by the motion system itself
    (the `scale-fade` preset degrades to opacity-only under `[data-motion='reduce']`
-   + `@media (prefers-reduced-motion)`), so no recipe-level override is needed. */
+   + `@media (prefers-reduced-motion)`), so no recipe-level override is needed.
+   The drag pickup-scale IS a recipe transition, so suppress it here — the shadow
+   lift alone still conveys the grab. */
+[data-motion='reduce'] [data-float-panel-content][data-dragging],
+[data-float-panel-content][data-dragging][data-motion='reduce'] {
+	scale: 1;
+	transition: none;
+}
+@media (prefers-reduced-motion: reduce) {
+	[data-float-panel-content][data-dragging] {
+		scale: 1;
+		transition: none;
+	}
+}

src/uix/eidos/eidos-motion.md

@@ -437,7 +437,7 @@ Tokens existentes (`STATIC_MOTION`, generados, leídos por css y js):
 | `--duration-{k}` | `instant 0` · `fast 120` · `normal 180` · `moderate 240` · `slow 320` ms |
 | `--ease-{k}` | `default` · `out` · `in` · `spring` · `alert` · `symmetric` |
 | `--motion-distance-{k}` | `xs 2` · `sm 4` · `md 8` · `lg 16` px |
-| `--motion-scale-{k}` | `enter 0.985` · `press 0.97` (fade-through usa `0.92` — F6 lo tokeniza) |
+| `--motion-scale-{k}` | `enter 0.985` · `press 0.97` · `through 0.92` (fade-through) · `lift 1.02` (pickup de drag — el único `>1`, ver §Draggable surfaces en THEMING) |
 
 **Vars de override (runtime, NO tokens de theme)** — un componente las pone en su
 elemento; el preset las lee con fallback al token:

src/uix/eidos/generated/base.css

@@ -229,6 +229,7 @@
 	--motion-scale-enter: 0.985;
 	--motion-scale-press: 0.97;
 	--motion-scale-through: 0.92;
+	--motion-scale-lift: 1.02;
 	--motion-stagger: 20ms;
 	--icon-size-xxs: calc(12px * var(--scaling));
 	--icon-size-xs: calc(14px * var(--scaling));

src/uix/eidos/lib/config-types.ts

@@ -509,7 +509,7 @@ export const EASE_KEYS = [
 	'emphasized'
 ] as const;
 export const MOTION_DISTANCE_KEYS = ['xs', 'sm', 'md', 'lg', 'xl'] as const;
-export const MOTION_SCALE_KEYS = ['enter', 'press', 'through'] as const;
+export const MOTION_SCALE_KEYS = ['enter', 'press', 'through', 'lift'] as const;
 export const ICON_STROKE_WIDTH_KEYS = ['sm', 'md', 'lg'] as const;
 
 export type DurationKey = (typeof DURATION_KEYS)[number];

src/uix/eidos/lib/primitives/static.ts

@@ -157,7 +157,12 @@ export const STATIC_MOTION = {
 		enter: '0.985',
 		press: '0.97',
 		// Fade-through (Material) incoming scale.
-		through: '0.92'
+		through: '0.92',
+		// Pickup LIFT — a grabbed surface scales slightly TOWARD the viewer (depth
+		// "picked up" cue). Cross-component: any draggable surface (float-panel,
+		// a slider thumb, a sortable item…) applies it on its grab/drag state,
+		// paired with an elevation shadow. >1 (the only grow in the scale family).
+		lift: '1.02'
 	},
 	stagger: '20ms',
 	// Expressive set (Carbon's productive/expressive split): emphasized easing

src/uix/soma/components/float-panel/float-panel-provider.svelte.ts

@@ -1019,7 +1019,7 @@ export class FloatPanelContentProvider {
 			el.style.top = '0px';
 			el.style.pointerEvents = 'auto';
 			el.style.zIndex = String(p.zIndex);
-			el.style.willChange = active ? 'translate' : '';
+			el.style.willChange = active ? 'translate, scale' : '';
 			el.style.userSelect = active ? 'none' : '';
 			// Geometry: only when no gesture is driving the element directly.
 			// Round to whole pixels — `translate` is a transform and doesn't snap to