Track your dues and residues, financially.
App structure:
residue/
├── index.html ← Single entry point
├── css/
│ └── main.css ← All styles
├── js/
│ ├── crypto.js ← AES-256-GCM via Web Crypto API
│ ├── storage.js ← IndexedDB vault (encrypted at rest)
│ ├── ui.js ← DOM helpers, toast, drag-drop
│ ├── pdf.js ← Local PDF parsing (PDF.js CDN)
│ └── app.js ← Main controller
└── assets/ ← Icons, fonts (if self-hosting)