fix: declare landing page as light-only to prevent dark theme extension issues

The landing page has no dark mode support, so browser extensions like
Dark Reader force-invert colors and break the design. This adds
color-scheme: light only in both CSS and meta tags, plus a
darkreader-lock meta tag, to signal that the page should not be
auto-darkened.

apps/landing/src/app/layout.tsx

@@ -10,6 +10,10 @@ export const metadata: Metadata = {
   description:
     "48 image processing tools with local AI. Runs 100% offline. No data leaves your network. Open source and free forever.",
   metadataBase: new URL("https://snapotter.com"),
+  other: {
+    "color-scheme": "light only",
+    "darkreader-lock": "true",
+  },
   openGraph: {
     title: "SnapOtter | Self-Hosted Image Processing",
     description:

apps/landing/src/styles/globals.css

@@ -1,5 +1,9 @@
 @import "tailwindcss";
 
+html {
+  color-scheme: light only;
+}
+
 @theme {
   --color-accent: #f59e0b;
   --color-accent-hover: #d97706;