Add persistent account navigation (sidebar/tabs); fix CTA arrow on Android

Konto-Aktionen links (profile, wishlist, logout) used to live at the bottom of the orders page's own content — unreachable once the order list got long enough. New KontoShell + AccountNav give every /konto/* page a persistent sidebar (sm+) / tab bar (mobile) instead, always reachable regardless of list length. The order filters also collapse behind a "Filter" toggle on mobile now, since the tab bar above them left little room for 3 full-width dropdowns.

Also: replaced the Unicode "→" arrow in CTA links (Tools.tsx, Blog.tsx, ProductGrid.tsx) with an SVG icon — the glyph isn't covered by the site's custom fonts, so browsers fall back to a system font per-platform; confirmed sitting visibly low relative to the label text on Android/Chrome (Galaxy S22), not reproducible in desktop Chromium. An SVG has no font-fallback path, so it renders identically everywhere.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/components/Tools.tsx

@@ -1,6 +1,7 @@
 import Link from "next/link";
 import Image from "next/image";
 import { Reveal, RevealGroup, RevealItem } from "./Reveal";
+import { ArrowRightIcon } from "./ArrowRightIcon";
 import { getWerkzeugeCards } from "../lib/payload";
 
 // Content now lives in Payload (WerkzeugeCards collection). Icons use a
@@ -87,17 +88,14 @@ export async function Tools() {
                   {tool.description}
                 </p>
               </div>
-              {/* flex items-center + arrow as its own span, not inline text
-                  — the → glyph sits low relative to the surrounding text's
-                  cap-height in the font used here, off-center against the
-                  label if it's just part of the same text node (fixed
-                  2026-07-24, same pattern ProductGrid.tsx's "Mehr
-                  erfahren" link already uses). */}
+              {/* SVG arrow, not a Unicode "→" character — see
+                  ArrowRightIcon.tsx's own comment on why (font-fallback
+                  vertical-metrics mismatch, platform-dependent). */}
               <Link
                 href={tool.ctaHref}
                 className="flex items-center gap-1 font-bold leading-normal text-body whitespace-nowrap hover:text-brand transition-colors"
               >
-                <span aria-hidden>→</span>
+                <ArrowRightIcon />
                 <span>{tool.ctaLabel}</span>
               </Link>
             </div>