feat: localise scan screen (12 languages)

Replace all hardcoded Russian strings in ScanScreen and _LoadingDialog
with AppLocalizations keys; add addFromReceiptOrPhoto, chooseMethod,
photoReceipt, photoReceiptSubtitle, photoProducts, photoProductsSubtitle,
recognizing keys to all 12 ARB files and regenerate AppLocalizations.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/lib/l10n/app_hi.arb

@@ -96,5 +96,11 @@
   "mealTypeSnack": "स्नैक",
   "navHome": "होम",
   "navProducts": "उत्पाद",
-  "navRecipes": "रेसिपी"
+  "navRecipes": "रेसिपी",
+  "addFromReceiptOrPhoto": "रसीद या फ़ोटो से जोड़ें",
+  "chooseMethod": "तरीका चुनें",
+  "photoReceipt": "रसीद की फ़ोटो",
+  "photoReceiptSubtitle": "रसीद से सभी उत्पाद पहचानें",
+  "photoProducts": "उत्पादों की फ़ोटो",
+  "photoProductsSubtitle": "फ्रिज, टेबल, शेल्फ — 3 फ़ोटो तक"
 }