fix: AppHeader usa <Link> para navegación SPA (no full reload); mock en tests de ReportPage

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/AppHeader.tsx

@@ -1,3 +1,5 @@
+import { Link } from '@tanstack/react-router'
+
 export function AppHeader() {
   return (
     <header
@@ -12,15 +14,15 @@ export function AppHeader() {
         flexShrink: 0,
       }}
     >
-      <a href="/" style={{ display: 'flex', alignItems: 'center' }}>
+      <Link to="/" style={{ display: 'flex', alignItems: 'center' }}>
         <img
           src="/inquality-logo-white.png"
           alt="InQuality"
           style={{ height: 24, objectFit: 'contain', cursor: 'pointer' }}
         />
-      </a>
-      <a
-        href="/"
+      </Link>
+      <Link
+        to="/"
         style={{
           color: 'white',
           fontSize: 13,
@@ -31,7 +33,7 @@ export function AppHeader() {
         }}
       >
         InQ ROI
-      </a>
+      </Link>
     </header>
   )
 }