fix(scanner): publish per-set usage freshness (#6432)

* fix(scanner): publish partial usage observations

* fix(ecstore): preserve quota baseline across restart

* style: format usage freshness changes

* fix(scanner): correct observational usage arguments

---------

Co-authored-by: houseme <housemecn@gmail.com>

crates/scanner/src/scanner.rs

@@ -2274,9 +2274,8 @@ async fn final_data_usage_publication_defer_reason(
             }
         }
         ScannerCycleStatus::Deferred(reason) => Some(reason),
-        // Incomplete cycles do not publish a usage snapshot. Keep the
-        // decision permissive so existing partial-cycle handling remains
-        // unchanged if a future scanner path emits a bookkeeping update.
+        // Incomplete cycles may publish a non-authoritative observational
+        // snapshot when at least one set has a usable current/LKG view.
         ScannerCycleStatus::Incomplete => None,
     }
 }