Move Borg repo to local backups and remove JuiceFS

Use /mnt/borg-backups in place of /mnt/object_storage for Borg.

Remove JuiceFS and Redis artifacts (tasks, templates, service configs)
and delete borg-local-sync tooling. Update borg-backup service
ReadWritePaths, remove Plex slow tvshows mount, add system sysctl
performance tunings, and apply minor code and flake.lock updates.

bin/actions/source.py

@@ -3,8 +3,8 @@
 """Generate export commands for Borg environment variables."""
 
 import os
-import sys
 import subprocess
+import sys
 
 # Add the bin directory to the path
 sys.path.append(os.path.join(os.path.dirname(__file__), ".."))
@@ -45,7 +45,7 @@ def main():
 
     # Generate the export commands
     exports = [
-        'export BORG_REPO="/mnt/object_storage/borg-repo"',
+        'export BORG_REPO="/mnt/borg-backups"',
         f'export BORG_PASSPHRASE="{passphrase}"',
         'export BORG_CACHE_DIR="/home/menno/.config/borg/cache"',
         'export BORG_CONFIG_DIR="/home/menno/.config/borg/config"',