Localize common UI components (bottom sheets)

Replace all hardcoded Korean text with i18n translation keys in
common bottom sheet components for email selection and download
type selection.

Components localized:
- email-bottom-sheet: Title, image save label, receive by email label,
  image requested snackbar message, close button alt, request button
- download-type-bottom-sheet: Title, download method selection labels,
  image/email alt texts, close button alt

Translation keys added to en.json:
- selectEmailAddress: "Select Email Address"
- imageSave: "Save as Image"
- receiveByEmail: "Receive by Email"
- mail: "Mail"
- image: "Image"
- request: "Request"
- imageRequested: "Image has been requested."
- selectDownloadMethod: "Select Download Method"

All bottom sheet UI text now supports internationalization.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/locales/en.json

@@ -27,7 +27,15 @@
             "fri": "Fri",
             "sat": "Sat"
         },
-        "currencyUnit": ""
+        "currencyUnit": "",
+        "selectEmailAddress": "Select Email Address",
+        "imageSave": "Save as Image",
+        "receiveByEmail": "Receive by Email",
+        "mail": "Mail",
+        "image": "Image",
+        "request": "Request",
+        "imageRequested": "Image has been requested.",
+        "selectDownloadMethod": "Select Download Method"
     },
     "menu": {
         "home": "Home",