Fix NIP-46 QR code styling to use tokenized colors and utility classes

Updated `js/ui/loginModalController.js` to resolve QR code colors from CSS variables (`--color-white`, `--color-black`) instead of hardcoding hex values, ensuring compatibility with the design system.
Updated `components/login-modal.html` to use Tailwind utility classes (`bg-white`, `text-black`, `p-6`) instead of inline styles, improving maintainability and readability.
This ensures the QR code remains scannable (high contrast) while respecting the codebase's tokenized styling approach.

components/login-modal.html

@@ -348,8 +348,7 @@
           <div data-nip46-handshake-panel class="space-y-6">
             <div class="flex flex-col items-center gap-6">
               <div
-                class="flex aspect-square w-full max-w-xs items-center justify-center rounded-2xl border border-border-strong bg-white p-6 shadow-sm"
-                style="background-color: white; color: black;"
+                class="flex aspect-square w-full max-w-xs items-center justify-center rounded-2xl border border-border-strong bg-white text-black p-6 shadow-sm"
                 data-nip46-qr
                 aria-hidden="true"
               >

js/ui/loginModalController.js

@@ -1299,8 +1299,21 @@ export default class LoginModalController {
         qrContainer.innerHTML = "";
         // Force high-contrast black-on-white for the QR code to ensure
         // it remains readable and scannable regardless of the application theme.
-        const qrLightColor = "#ffffff";
-        const qrDarkColor = "#000000";
+        // We resolve these from the unified token system to ensure consistency.
+        let qrLightColor = "#ffffff";
+        let qrDarkColor = "#000000";
+
+        if (this.window && typeof this.window.getComputedStyle === "function") {
+          try {
+            const style = this.window.getComputedStyle(this.document.documentElement);
+            const white = style.getPropertyValue("--color-white").trim();
+            const black = style.getPropertyValue("--color-black").trim();
+            if (white) qrLightColor = white;
+            if (black) qrDarkColor = black;
+          } catch (error) {
+            // Fallback to hardcoded values if style resolution fails
+          }
+        }
 
         if (uri) {
           try {