fix(scale): auto-fill broken for conf products (e.g. latte)

Two root causes:
1. _useNormalUnit was stale ('pz') for conf products because it's only
   updated in normal mode — fix: resolve effective unit from
   _useConfMode.packageUnit when in sub mode
2. Food scales in liquid mode send unit='ml' directly — was falling
   through to raw value, skipping density; fix: detect scaleAlreadyMl
   flag to use ml directly for ml target, or apply density for g target
Also: add scale pre-fill call after switchUseUnit('sub') in conf mode

index.html

@@ -1239,6 +1239,6 @@
     </div>
 </div>
 
-<script src="assets/js/app.js?v=20260415e"></script>
+<script src="assets/js/app.js?v=20260415f"></script>
 </body>
 </html>