Rename app from SatDetect to AI Change Detection

Add 3D building analysis: shadow-based height/stories estimation and construction stage classification

Sticky nav, avatar dropdown menu, mobile responsive layout

New gradient theme: #2e33c5 to #cf2040 across nav, footer, buttons, and all accents

Simplify password eye to single grey icon, move forgot below sign-in, remove or divider

Polish forgot password and password toggle UI to match design system

Add forgot password flow and password visibility toggle

Initial commit: SatDetect satellite change detection web app