Add product website (deploy target: noo.ayushya.dev)

A single-page, static site under website/ - no build step, no
framework, just HTML/CSS/vanilla JS plus the two Google Fonts the app
already uses. Colors, radii, type scale and motion timing are copied
from lib/theme/design_tokens.dart so it reads as the same product as
the app, not a separate marketing skin.

Sections: hero with an exploded, parallaxing stack of the app's own UI
pieces (file row, photo grid, accent swatches, a toggle, the floating
bar) that drift apart on scroll and tilt toward the pointer; feature
highlights; a Customize section with two live interactive demos
(accent color, floating vs attached bottom bar); a privacy section
covering Login Flow v2; and a closing CTA.

GitHub/download links are placeholders (documented in website/README.md)
until real release URLs exist.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

website/favicon.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32">
+  <rect width="32" height="32" rx="9" fill="#8D0DE3"/>
+  <rect x="9" y="9" width="14" height="14" rx="5" fill="#FFFFFF" fill-opacity="0.92"/>
+</svg>