feat(quick-add): save & add another for rapid manual entry

The quick-add sheet no longer closes on every save: a new 'Save & add
another' action saves the seed, clears the form (keeping the chosen lot
type), refocuses the name field and shows an 'N added' running count, so
a whole shelf can be entered without reopening the sheet each time.
Plain Save still closes it. Adds a dedicated label field with its own
controller, submitAndAddAnother() on the cubit, and cubit + widget tests.

apps/app_seeds/lib/i18n/es.i18n.json

@@ -122,6 +122,8 @@
     "quantity": "¿Cuánta?",
     "more": "Añadir más…",
     "save": "Guardar",
+    "saveAndAddAnother": "Guardar y añadir otra",
+    "addedCount": "{n} añadidas",
     "cancel": "Cancelar"
   },
   "detail": {