restore(mobile): restore mobile/ directory to pre-d2217531 state

Restored mobile/ from d22175310a711e7ebdd8062ae29a54f0136dc3f6^
(parent commit d94e9ca4bc).

Commit d22175310a (google-labs-jules[bot], 2026-03-23T14:45:22Z) introduced
an SSRF security fix for IMAP connections but unintentionally deleted or
truncated a large number of files across the repository, including 24 files
under mobile/.

This commit targets only the mobile/ directory and restores the following
files to their pre-d2217531 state:

- mobile/README.md
- mobile/app.json
- mobile/app/(tabs)/_layout.tsx
- mobile/app/(tabs)/file-detail.tsx  (re-added)
- mobile/app/+not-found.tsx          (re-added)
- mobile/app/_layout.tsx
- mobile/eslint.config.js            (re-added)
- mobile/package-lock.json
- mobile/package.json
- mobile/src/context/ShareContext.tsx
- mobile/src/i18n/de.json            (re-added)
- mobile/src/i18n/en.json            (re-added)
- mobile/src/i18n/es.json            (re-added)
- mobile/src/i18n/fr.json            (re-added)
- mobile/src/i18n/index.ts           (re-added)
- mobile/src/i18n/it.json            (re-added)
- mobile/src/screens/FileDetailScreen.tsx (re-added)
- mobile/src/screens/FilesScreen.tsx
- mobile/src/screens/LoginScreen.tsx
- mobile/src/screens/ProfileScreen.tsx
- mobile/src/screens/UploadScreen.tsx
- mobile/src/screens/WelcomeScreen.tsx
- mobile/src/services/api.ts
- mobile/src/utils/mimeTypes.ts      (re-added)
- mobile/src/utils/normalizeUri.ts   (re-added)

Security fixes introduced by d2217531 that are unrelated to mobile/
(IMAP SSRF fix in app/utils/network.py and app/tasks/imap_tasks.py)
are preserved — this restore targets only files under mobile/.

mobile/app/(tabs)/_layout.tsx

@@ -11,10 +11,15 @@ import { Ionicons } from "@expo/vector-icons";
 import React from "react";
 import { usePushNotifications } from "../../src/hooks/usePushNotifications";
 import { useAuth } from "../../src/context/AuthContext";
+import { useLocale, t } from "../../src/i18n";
 
 export default function TabLayout() {
   const { isAuthenticated } = useAuth();
   usePushNotifications(isAuthenticated);
+  // Subscribe to language changes so tab labels re-render when the language
+  // is switched.  The `lang` variable is intentionally unused – its only
+  // purpose is to make this component a consumer of LocaleContext.
+  useLocale();
 
   return (
     <Tabs
@@ -37,8 +42,8 @@ export default function TabLayout() {
       <Tabs.Screen
         name="index"
         options={{
-          title: "Upload",
-          tabBarLabel: "Upload",
+          title: t("tabs.upload"),
+          tabBarLabel: t("tabs.upload"),
           tabBarIcon: ({ color, size }) => (
             <Ionicons name="cloud-upload-outline" size={size} color={color} />
           ),
@@ -48,23 +53,32 @@ export default function TabLayout() {
       <Tabs.Screen
         name="files"
         options={{
-          title: "Files",
-          tabBarLabel: "Files",
+          title: t("tabs.files"),
+          tabBarLabel: t("tabs.files"),
           tabBarIcon: ({ color, size }) => (
             <Ionicons name="document-text-outline" size={size} color={color} />
           ),
-          headerTitle: "My Documents",
+          headerTitle: t("files.title"),
         }}
       />
       <Tabs.Screen
         name="profile"
         options={{
-          title: "Profile",
-          tabBarLabel: "Profile",
+          title: t("tabs.profile"),
+          tabBarLabel: t("tabs.profile"),
           tabBarIcon: ({ color, size }) => (
             <Ionicons name="person-circle-outline" size={size} color={color} />
           ),
-          headerTitle: "Profile",
+          headerTitle: t("tabs.profile"),
+        }}
+      />
+      {/* File detail screen – hidden from tab bar, accessed via navigation */}
+      <Tabs.Screen
+        name="file-detail"
+        options={{
+          href: null,
+          title: t("file_detail.title"),
+          headerTitle: t("file_detail.title"),
         }}
       />
     </Tabs>