Idea 7: Local Encrypted Vault for Notes & Notebooks

Problem: Joplin’s End-to-End Encryption (E2EE) secures data during sync, but notes remain in plaintext within the local SQLite database. This leaves sensitive data vulnerable to local filesystem access on shared, corporate, or unlocked devices. Solution: This project implements a Local Encrypted Vault using a "Body-Prefix Polymorphism" strategy. Instead of fragile database schema migrations, notes are locked via AES-256-GCM, and the ciphertext is stored directly in the native body field (e.g., JOPLIN_CIPHER:AF82D...). This architecture natively supports Joplin’s Stacked E2EE sync, prevents double-encryption bugs, and utilizes Just-In-Time (JIT) RAM decryption to ensure maximum security.