fix(grafico): HiloConductor a la banda lateral, con stacking explícito

El hilo pintaba encima del texto en las secciones sin position:relative
(Dolores, Disciplinas, Estratega, ComoEmpezar) y detrás del texto en las
que sí la tienen, por el orden de pintado del navegador. Se mueve a la
banda vacía a la izquierda de la columna max-w-content (oculto bajo 2xl,
donde no hay margen seguro) y gana un z-index explícito por debajo del
header.

components/primitives/HiloConductor.tsx

@@ -14,6 +14,20 @@ import { usePrefersReducedMotion } from '@/lib/motion';
 // Uses the page-level useScroll() with no target ref on purpose: no element
 // measuring, no "container has a static position" warnings, and one scroll
 // listener for the whole page.
+//
+// It lives in the empty margin band to the left of the centred
+// `max-w-content` (1152px) column, never over it — some sections are
+// `position: relative` for unrelated reasons and some are not, so an
+// absolutely-positioned overlay with no explicit stacking level paints
+// inconsistently: above the static sections, behind the relative ones. `z-30`
+// gives it its own stacking context that beats every section root regardless
+// of that accident, while staying under the sticky header's `z-50`.
+//
+// Hidden below `2xl` (1536px): that's the first breakpoint that guarantees a
+// safe margin outside the 1152px column — (1536 - 1152) / 2 = 192px per side,
+// comfortable room for the thread's own offset plus breathing space to the
+// viewport edge. Narrower viewports have no safe band, so the thread simply
+// doesn't render there rather than creeping over the text.
 
 const TRAZO =
   'M50 0 C 20 140, 80 260, 50 400 C 20 540, 80 660, 50 800 C 20 940, 80 1060, 50 1200';
@@ -23,50 +37,42 @@ export function HiloConductor({ className = '' }: { className?: string }) {
   const { scrollYProgress } = useScroll();
   const avance = useSpring(scrollYProgress, { stiffness: 90, damping: 30, restDelta: 0.001 });
 
-  const base = `pointer-events-none absolute inset-y-0 left-1/2 -translate-x-1/2 w-full max-w-content h-full ${className}`;
-
-  // The positioning/pointer-events classes live on a wrapping <div> rather
-  // than the <svg> itself: per spec `SVGElement.className` is an
-  // SVGAnimatedString, not a plain string, so tests (and any other reader of
-  // `.className`) can't inspect it as text. A plain HTMLElement keeps that
-  // contract simple.
+  // Percentage-based band geometry against the containing block, never
+  // `100vw` — `100vw` includes the scrollbar and would overshoot the real
+  // document width by ~15px on desktop. `inset-0` and the inner `mx-auto
+  // max-w-content` box both resolve against `<main>`'s own width instead.
+  const wrapper = `pointer-events-none absolute inset-0 z-30 hidden 2xl:block ${className}`;
 
   // Plain <path> for reduced motion: motion.path applies dash scaffolding even
   // without initial/animate and would leave the thread invisible.
-  if (reduced) {
-    return (
-      <div className={base}>
+  const trazo = reduced ? (
+    <path d={TRAZO} fill="none" stroke="currentColor" strokeWidth={1.5} strokeLinecap="round" />
+  ) : (
+    <motion.path
+      d={TRAZO}
+      fill="none"
+      stroke="currentColor"
+      strokeWidth={1.5}
+      strokeLinecap="round"
+      style={{ pathLength: avance }}
+    />
+  );
+
+  return (
+    <div className={wrapper}>
+      {/* Mirrors Container's own centring (`mx-auto max-w-content`) so the
+          band below is measured from the real column edge. */}
+      <div className="relative mx-auto h-full w-full max-w-content">
         <svg
-          className="h-full w-full text-dorado/25"
+          className="absolute inset-y-0 right-full mr-10 h-full w-14 text-dorado/25"
           viewBox="0 0 100 1200"
           preserveAspectRatio="none"
           aria-hidden="true"
           focusable="false"
         >
-          <path d={TRAZO} fill="none" stroke="currentColor" strokeWidth={1.5} strokeLinecap="round" />
+          {trazo}
         </svg>
       </div>
-    );
-  }
-
-  return (
-    <div className={base}>
-      <svg
-        className="h-full w-full text-dorado/25"
-        viewBox="0 0 100 1200"
-        preserveAspectRatio="none"
-        aria-hidden="true"
-        focusable="false"
-      >
-        <motion.path
-          d={TRAZO}
-          fill="none"
-          stroke="currentColor"
-          strokeWidth={1.5}
-          strokeLinecap="round"
-          style={{ pathLength: avance }}
-        />
-      </svg>
     </div>
   );
 }

components/primitives/__tests__/HiloConductor.test.tsx

@@ -1,8 +1,13 @@
 import { render } from '@testing-library/react';
-import { describe, it, expect } from 'vitest';
+import { describe, it, expect, afterEach } from 'vitest';
 import { HiloConductor } from '../HiloConductor';
 
 describe('<HiloConductor />', () => {
+  const matchMediaOriginal = window.matchMedia;
+  afterEach(() => {
+    window.matchMedia = matchMediaOriginal;
+  });
+
   it('is decorative: hidden from assistive tech', () => {
     const { container } = render(<HiloConductor />);
     const svg = container.querySelector('svg');
@@ -27,4 +32,59 @@ describe('<HiloConductor />', () => {
     const { container } = render(<HiloConductor />);
     expect(container.firstElementChild?.className).toContain('pointer-events-none');
   });
+
+  it('sits in the margin band beside the column, never over it', () => {
+    const { container } = render(<HiloConductor />);
+    const svg = container.querySelector('svg');
+    // `right-full` (`right: 100%`) anchors the thread's right edge to the
+    // left edge of the `max-w-content` column it shares a parent with —
+    // structurally outside the column, not merely visually offset within it.
+    // Read via getAttribute: on an SVGElement, `.className` is an
+    // SVGAnimatedString, not a plain string.
+    expect(svg?.getAttribute('class')).toContain('right-full');
+  });
+
+  it('declares a stacking level that beats section roots but stays under the header', () => {
+    const { container } = render(<HiloConductor />);
+    const wrapperClass = container.firstElementChild?.className ?? '';
+    // Section roots never set z-index (auto), so any explicit positive value
+    // paints above them regardless of whether the section itself happens to
+    // be `position: relative` or `static` — that inconsistency was the bug.
+    // The sticky header is z-50 and must still win.
+    expect(wrapperClass).toMatch(/\bz-\d+\b/);
+    expect(wrapperClass).not.toContain('z-50');
+  });
+
+  it('is hidden below the breakpoint that guarantees a safe margin', () => {
+    const { container } = render(<HiloConductor />);
+    const wrapperClass = container.firstElementChild?.className ?? '';
+    // No safe band exists under the content column's own breakpoint; hiding
+    // it there is what keeps it from ever creeping over the text.
+    expect(wrapperClass).toContain('hidden');
+    expect(wrapperClass).toContain('2xl:block');
+  });
+
+  it('renders a genuine plain path under reduced motion, not a neutralised motion.path', () => {
+    window.matchMedia = (query: string) =>
+      ({
+        matches: true,
+        media: query,
+        onchange: null,
+        addEventListener: () => {},
+        removeEventListener: () => {},
+        addListener: () => {},
+        removeListener: () => {},
+        dispatchEvent: () => false,
+      }) as unknown as MediaQueryList;
+
+    const { container } = render(<HiloConductor />);
+    const path = container.querySelector('path');
+    // motion.path stamps stroke-dasharray/stroke-dashoffset onto the DOM even
+    // without initial/animate — the dash-scaffolding trap that leaves the
+    // thread invisible for reduced-motion users. A real plain <path> never
+    // gets them, so their absence proves the branches weren't collapsed back
+    // into one.
+    expect(path).not.toHaveAttribute('stroke-dasharray');
+    expect(path).not.toHaveAttribute('stroke-dashoffset');
+  });
 });