Fix min quantity for kg/l units in use forms

- Normal mode (non-conf) now sets min=0.01 for kg/l, min=1 for g/ml
- +/- buttons use unit-aware steps: 0.01 for small kg/l values, 0.1 for
  values <1, 0.5 for values >=1 (instead of fixed 0.5)
- Same fix applied to recipe use form
- Allows inputting e.g. 0.07kg (70g) when product is tracked in kg

index.html

@@ -997,6 +997,6 @@
     </div>
 </div>
 
-<script src="assets/js/app.js?v=20260330a"></script>
+<script src="assets/js/app.js?v=20260330b"></script>
 </body>
 </html>