Fix filesystem metric parsing bounds error in dashboard

Prevent string slicing panic in extract_filesystem_metric when
parsing individual filesystem metrics. This resolves the issue
where filesystem entries show —% —GB/—GB instead of actual usage.

dashboard/src/ui/widgets/system.rs

@@ -391,8 +391,12 @@ impl SystemWidget {
                 
                 for suffix in known_suffixes {
                     if after_fs.ends_with(suffix) {
-                        let fs_name = after_fs[..after_fs.len() - suffix.len() - 1].to_string(); // Remove suffix + underscore
-                        return (Some(fs_name), Some(suffix.to_string()));
+                        // Safely calculate fs_name length
+                        let suffix_with_underscore = suffix.len() + 1;
+                        if after_fs.len() > suffix_with_underscore {
+                            let fs_name = after_fs[..after_fs.len() - suffix_with_underscore].to_string();
+                            return (Some(fs_name), Some(suffix.to_string()));
+                        }
                     }
                 }
             }