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/manifest.json

@@ -1,19 +1,29 @@
 {
-  "name": "Untrace",
+  "id": "/",
+  "name": "Untrace — content credentials and metadata remover",
   "short_name": "Untrace",
-  "description": "EXIF Metadata & AI Content Credential Remover",
+  "description": "Remove C2PA content credentials, AI generation tags and EXIF metadata from images, entirely in your browser.",
   "start_url": "/",
+  "scope": "/",
   "display": "standalone",
-  "background_color": "#ffffff",
-  "theme_color": "#3b82f6",
+  "background_color": "#080808",
+  "theme_color": "#080808",
   "icons": [
     {
-      "src": "vite.svg",
+      "src": "/favicon.svg",
       "sizes": "any",
-      "type": "image/svg+xml"
+      "type": "image/svg+xml",
+      "purpose": "any"
+    },
+    {
+      "src": "/favicon-maskable.svg",
+      "sizes": "any",
+      "type": "image/svg+xml",
+      "purpose": "maskable"
     }
   ],
   "categories": ["productivity", "utilities", "photo"],
   "lang": "en",
+  "dir": "ltr",
   "orientation": "any"
 }