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

public/favicon-16x16.svg

@@ -1,23 +1,5 @@
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-  <!-- Simplified version for 16x16 -->
-  <defs>
-    <linearGradient id="logoGradient16" x1="0%" y1="0%" x2="100%" y2="100%">
-      <stop offset="0%" style="stop-color:#3B82F6;stop-opacity:1" />
-      <stop offset="100%" style="stop-color:#1E40AF;stop-opacity:1" />
-    </linearGradient>
-  </defs>
-
-  <!-- Main circle background -->
-  <circle cx="24" cy="24" r="22" fill="url(#logoGradient16)" />
-
-  <!-- Simplified image icon -->
-  <rect x="12" y="16" width="24" height="16" rx="2" fill="white" opacity="0.9" />
-  
-  <!-- Strike-through line -->
-  <line x1="8" y1="8" x2="40" y2="40" stroke="#EF4444" stroke-width="4" stroke-linecap="round" />
-  <line x1="8" y1="8" x2="40" y2="40" stroke="white" stroke-width="2" stroke-linecap="round" />
-
-  <!-- Shield -->
-  <circle cx="38" cy="18" r="6" fill="#10B981" stroke="white" stroke-width="1.5" />
-  <path d="M36 18 L37 19 L40 16" stroke="white" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" />
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 48 48" role="img" aria-label="Untrace">
+  <rect width="48" height="48" rx="10" fill="#3450C8"/>
+  <text x="24" y="24" fill="#FFFFFF" font-family="'IBM Plex Mono', ui-monospace, monospace"
+        font-size="28" font-weight="600" text-anchor="middle" dominant-baseline="central">U</text>
 </svg>