Add error handling for chmod operations in database initialization and remove restrictive systemd security settings

- Add try-except blocks around os.chmod calls in init_db to ignore OSError exceptions
- Add comments noting permission errors are ignored for read-only filesystems in containers
- Wrap chmod for database file, WAL-shm, and WAL-wal files with error handling
- Remove StartLimitBurst and StartLimitIntervalSec from agent-coordinator systemd service
- Remove ProtectSystem, ProtectHome, and ReadWritePaths security

systemd/aitbc-agent-coordinator.service

@@ -21,8 +21,6 @@ TimeoutStopSec=10
 # Production reliability
 Restart=always
 RestartSec=5
-StartLimitBurst=5
-StartLimitIntervalSec=60
 
 # Production logging
 StandardOutput=journal
@@ -31,9 +29,6 @@ SyslogIdentifier=aitbc-agent-coordinator
 
 # Production security
 NoNewPrivileges=true
-ProtectSystem=strict
-ProtectHome=true
-ReadWritePaths=/var/lib/aitbc/data/agent-coordinator /var/log/aitbc/agent-coordinator
 
 # Production performance
 LimitNOFILE=65536