Converts the Source Health last-check column and the Downloads created-at
column from locale date strings to human-relative times ("6 hours ago").
The absolute timestamp is preserved as a native browser tooltip so full
precision is still one hover away; detail modals keep the absolute form.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Replace all bare `session = AsyncSession(bind=conn)` assignments with
`async with AsyncSession(bind=conn) as session:` in downloads.py,
credentials.py, settings.py, sources.py, and subscriptions.py to
ensure sessions are properly closed on all code paths.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
bvandeusen
Bryan Van Deusen