feat(photos): camera-or-gallery picker + swipeable full-screen viewer

- Adding a photo (quick-add and detail) now offers a Camera / Gallery chooser
  (shared pickPhoto helper); camera errors on desktop degrade gracefully.
- Full-screen viewer: pinch-to-zoom pans only while zoomed, so a plain
  horizontal swipe pages between photos again.

54 tests green; Linux runs.

apps/app_seeds/lib/i18n/en.i18n.json

@@ -14,6 +14,10 @@
     "openMarket": "Open market",
     "yourInventory": "Your inventory"
   },
+  "photo": {
+    "camera": "Take a photo",
+    "gallery": "Choose from gallery"
+  },
   "menu": {
     "inventory": "Inventory",
     "market": "Market",