Fix filesystem usage_percent parsing and remove hardcoded status

1. Add missing _fs_ filter to usage_percent parsing in dashboard
2. Fix agent to use calculated fs_status instead of hardcoded Status::Ok

This completes the disk collector auto-discovery by ensuring filesystem
usage percentages and status indicators display correctly.

agent/src/collectors/disk.rs

@@ -695,7 +695,7 @@ impl DiskCollector {
                 value: MetricValue::Float(self.bytes_to_gb(filesystem.used_bytes)),
                 unit: Some("GB".to_string()),
                 description: Some(format!("{}: {}", filesystem.mount_point, self.bytes_to_human_readable(filesystem.used_bytes))),
-                status: Status::Ok,
+                status: fs_status.clone(),
                 timestamp,
             });
 
@@ -704,7 +704,7 @@ impl DiskCollector {
                 value: MetricValue::Float(self.bytes_to_gb(filesystem.total_bytes)),
                 unit: Some("GB".to_string()),
                 description: Some(format!("{}: {}", filesystem.mount_point, self.bytes_to_human_readable(filesystem.total_bytes))),
-                status: Status::Ok,
+                status: fs_status.clone(),
                 timestamp,
             });