Feature: Prepare for v1.2 release

[simmsa]

v1.2.0

• S3 file downloads: download files directly from the S3 browser.
• Large upload to existing folder: target an existing S3 prefix when running a large folder sync, not just newly created folders.
• Application log syncing: app logs and global frontend/backend errors are captured and uploaded to S3 for diagnostics.
• Per-user event logs: unique event logs are generated for each user.
• Faster S3 browsing: more efficient S3 listing strategy plus frontend improvements for the file browser.
• OS-standard log directories: logs now use platform-standard locations.