Run cargo fmt on the unit code and drop a quantity box's invalid mark when its line is removed

The new CI runs cargo fmt --check. QuantityInput also reported its validity only when it changed, so removing a line
whose quantity box held bad text left that box counted as invalid and blocked issuing; it now reports valid when it
unmounts, and no longer writes a ref during render.

Claude-Session: https://claude.ai/code/session_01PZypiWDfMkDTeEPeXjRhW5

src-tauri/src/db.rs

@@ -1108,7 +1108,17 @@ CREATE INDEX IF NOT EXISTS idx_invoices_created ON invoices(created_at DESC);
     fn m12_rebuilds_item_presets_keeping_rows_and_allowing_new_units() {
         let mut conn = Connection::open_in_memory().unwrap();
         let v11 = vec![
-            M::up(SCHEMA), M::up(M2), M::up(M3), M::up(M4), M::up(M5), M::up(M6), M::up(M7), M::up(M8), M::up(M9), M::up(M10), M::up(M11),
+            M::up(SCHEMA),
+            M::up(M2),
+            M::up(M3),
+            M::up(M4),
+            M::up(M5),
+            M::up(M6),
+            M::up(M7),
+            M::up(M8),
+            M::up(M9),
+            M::up(M10),
+            M::up(M11),
         ];
         Migrations::new(v11).to_latest(&mut conn).unwrap();
         assert_eq!(user_version(&conn), 11);
@@ -1134,16 +1144,43 @@ CREATE INDEX IF NOT EXISTS idx_invoices_created ON invoices(created_at DESC);
         assert_eq!(
             rows,
             vec![
-                (1, "Studio".into(), "998397".into(), "rate".into(), "hour".into(), 150050, 3, "then".into(), Some("ITEM-1".into())),
-                (2, "Fee".into(), "".into(), "fixed".into(), "unit".into(), 500000, 0, "then".into(), None),
+                (
+                    1,
+                    "Studio".into(),
+                    "998397".into(),
+                    "rate".into(),
+                    "hour".into(),
+                    150050,
+                    3,
+                    "then".into(),
+                    Some("ITEM-1".into())
+                ),
+                (
+                    2,
+                    "Fee".into(),
+                    "".into(),
+                    "fixed".into(),
+                    "unit".into(),
+                    500000,
+                    0,
+                    "then".into(),
+                    None
+                ),
             ]
         );
         // New units and custom text are allowed; an empty or over-long unit is not; ids keep counting up.
         conn.execute("INSERT INTO item_presets (description, unit, created_at) VALUES ('Travel', 'km', 'now')", []).unwrap();
         conn.execute("INSERT INTO item_presets (description, unit, created_at) VALUES ('Parcel', 'bundle', 'now')", []).unwrap();
-        assert!(conn.execute("INSERT INTO item_presets (description, unit, created_at) VALUES ('X', '', 'now')", []).is_err());
+        assert!(conn
+            .execute(
+                "INSERT INTO item_presets (description, unit, created_at) VALUES ('X', '', 'now')",
+                []
+            )
+            .is_err());
         assert!(conn.execute("INSERT INTO item_presets (description, unit, created_at) VALUES ('X', 'thirteen char', 'now')", []).is_err());
-        let last: i64 = conn.query_row("SELECT MAX(id) FROM item_presets", [], |r| r.get(0)).unwrap();
+        let last: i64 = conn
+            .query_row("SELECT MAX(id) FROM item_presets", [], |r| r.get(0))
+            .unwrap();
         assert_eq!(last, 4);
     }