Add pothole detection as new menu type with separate engine and research plan

Add landslide detection menu, separate engine, and Uttarakhand integration plan

Use manager email API for notifications (multipart/form-data); SMTP fallback

Revert Resend; use SMTP only, custom email API to be integrated later

Use Resend HTTPS API for email (HF Spaces); SMTP fallback for local

HF fix: uvicorn-only CMD, defensive mkdir, remove unused numpy, overlay mkdir on save, README troubleshooting

Rename app from SatDetect to AI Change Detection

Fix HF metadata: use valid colorTo value

Add Hugging Face Spaces support (Docker, port 7860, non-root user)

Initial commit: SatDetect satellite change detection web app