style: treefmt main — fix CI formatting check

Full `nix flake check` (CI) runs the treefmt formatting derivation. While the
hive-ci runner was offline (#1221), PRs merged without it, leaving 5 files
unformatted: hive-ag3nt/src/web_ui.rs, hive-c0re/src/bin/hivectl.rs,
hive-c0re/src/knowledge.rs, hive-c0re/src/matrix.rs,
hive-forge/src/verbs/attachment_get.rs. `nix fmt` output, pure formatting.

hive-ag3nt/src/web_ui.rs

@@ -618,7 +618,11 @@ fn read_own_status() -> (Option<String>, Option<i64>) {
                 .and_then(|d| i64::try_from(d.as_secs()).ok())
         })
     });
-    if text.is_none() { (None, None) } else { (text, mtime) }
+    if text.is_none() {
+        (None, None)
+    } else {
+        (text, mtime)
+    }
 }
 
 async fn api_dashboard_state(State(state): State<AppState>) -> axum::Json<DashboardState> {