cloud_session.py: no-op in local mode; in cloud mode resolves Directus JWT
from X-CF-Session header to per-user db_path in st.session_state.
get_connection() in scripts/db.py: transparent SQLCipher/sqlite3 switch —
uses encrypted driver when CLOUD_MODE=true and key provided, vanilla sqlite3
otherwise. libsqlcipher-dev added to Dockerfile for Docker builds.
6 new cloud_session tests + 1 new get_connection test — 34/34 db tests pass.
