feat(auth): redesign Login and Setup pages with split-panel branding layout (#168)

* feat(auth): redesign Login and Setup pages with split-panel branding layout

Replace plain Card-based Login and Setup forms with a professional
split-panel layout: always-dark branding panel (dot grid texture, logo,
tagline, cyan accent line) on the left, theme-aware form on the right.
Mobile collapses to single column with compact logo header.

- Add optional admin email field on Setup for license recovery
- Backend accepts and stores admin_email in setup endpoint
- Fix data-stacks-loaded attribute forwarding (wrap in div, use string values)

* docs: add license-settings and profile-dropdown screenshots

* fix(docs): correct logo paths from .svg to .png

* fix(deps): resolve picomatch high-severity vulnerability

frontend/package-lock.json

@@ -4980,9 +4980,9 @@
       "license": "ISC"
     },
     "node_modules/picomatch": {
-      "version": "4.0.3",
-      "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-4.0.3.tgz",
-      "integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
+      "version": "4.0.4",
+      "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-4.0.4.tgz",
+      "integrity": "sha512-QP88BAKvMam/3NxH6vj2o21R6MjxZUAd6nlwAS/pnGvN9IVLocLHxGYIzFhg6fUQ+5th6P4dv4eW9jX3DSIj7A==",
       "dev": true,
       "license": "MIT",
       "engines": {