Fix notify_to env var name (fallback)

Add PDF upload endpoint for worker

deploy: sync api from pdf-trainer-demo

fix: remove cache files and restore backend package

deploy: real pdf-trainer-demo API

demo(A): local pdf storage + PUT/GET /api/pdf

fix: import Header for worker auth

api: accept PDF uploads + serve PDFs locally

debug: /api/sftp-test returns JSON on connect failure

debug: real /api/sftp-test with socket+paramiko timeouts

debug: add /api/sftp-test

cleanup: remove dead code after /api/pdf return

fix: make /api/pdf serve from SFTP with timeout

fix: add SFTP timeouts + prevent /api/pdf hang

fix: remove bogus SFTPStore import

api: serve pdfs from SFTP for trainer UI

api: add SFTP download helper

fix: proper empty 204 response for jobs/next

SFTP: serve PDFs + store configs in /inserio

phase2: add worker job queue endpoints

refactor: clean API, lazy-load worker deps

refactor: lazy-load GmailClient to decouple API startup

integrate real backend api