Rebuild on the RealBrain design system and retarget SEO to content credentials

Search Console (Jun 4 – Sep 3) shows the page ranking on the first results
page for "content credentials" queries while converting badly: "ai
credentials remover" at 113 impressions and 0.88% CTR from position 6.7,
"remove content credentials from image online" at 2.15% from position 5.0,
"remove ai content credentials from image" at 0% from position 7.8. The
title led with "EXIF metadata", a phrase that appears in none of the top
queries, so the snippet never matched the intent behind the impressions.

SEO
- Title, description and H1 rebuilt around "remove content credentials from
  an image"; EXIF kept as a secondary term.
- Added a how-to section and a nine-question FAQ answering the question
  queries that had no content behind them, including the LinkedIn AI label
  and the Instagram AI tag.
- Structured data as an @graph: WebSite (alternateName "Untrace AI" for the
  unserved brand query), Organization, WebApplication, HowTo, FAQPage.
- Fixed sitemap.xml, which pointed at /untrace/ — a URL that does not exist.
- Regenerated the Open Graph image to match the new design.

Design
- Vendored the design system at src/tokens.css and composed the app from it.
  The old styling broke most of its rules: gradients, font weights 800 and
  900, raw #2563eb, Inter, and emoji as the only status signal.
- Reworked the tool into a Scan / Review / Download flow that lists what it
  found before changing anything, with the primary action pinned within
  thumb reach on small screens.
- Dark by default with a light theme, applied before first paint so the page
  never flashes the wrong surface.
- Replaced the floating donation widget, which painted an off-token circle
  over the page and covered the mobile action bar, with a footer link.

Structure
- Moved detection into src/lib/metadata.js and removal into src/lib/clean.js;
  the canvas callbacks are now a promise chain.
- Dropped Tailwind and PostCSS. Both were configured twice, and no Tailwind
  utility was used. Stylesheet is 6.2 kB gzipped with the whole system in it.

Fixes
- The stepper never advanced: stepState(index) read `current` from the
  closure, which Svelte 4 cannot track as a template dependency.
- The cleaner's fallback returned the original, uncleaned file while the UI
  reported "All EXIF metadata removed". It now reports the failure instead.

Verified against a JPEG carrying EXIF, GPS, XMP and an APP11 JUMBF C2PA
manifest: the output retains only APP0 and the sRGB ICC profile, with every
provenance marker gone.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018pRSdR57Ze9M2meDfYZgYE

src/lib/TopBar.svelte

@@ -0,0 +1,53 @@
+<script>
+  import ThemeToggle from "./ThemeToggle.svelte";
+  import Icon from "./Icon.svelte";
+</script>
+
+<header class="topbar">
+  <div class="wrap inner">
+    <a class="wordmark" href="/" aria-label="Untrace home">
+      <span class="r-mark" aria-hidden="true">U</span>
+      <span>Untrace</span>
+    </a>
+
+    <nav class="actions" aria-label="Site">
+      <a
+        class="btn btn-ghost repo"
+        href="https://github.com/developersharif/untrace"
+        target="_blank"
+        rel="noopener noreferrer"
+      >
+        <Icon name="github" size="sm" />
+        <span>Source</span>
+      </a>
+      <ThemeToggle />
+    </nav>
+  </div>
+</header>
+
+<style>
+  .actions {
+    display: flex;
+    align-items: center;
+    gap: var(--space-2);
+  }
+
+  .repo {
+    height: var(--space-8);
+    padding-inline: var(--space-3);
+  }
+
+  .repo:hover {
+    text-decoration: none;
+  }
+
+  .repo span {
+    display: none;
+  }
+
+  @media (min-width: 560px) {
+    .repo span {
+      display: inline;
+    }
+  }
+</style>