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/README.md

@@ -163,6 +163,16 @@ The app registers itself as a share target so any file can be sent directly to D
 
 The root layout (`app/_layout.tsx`) listens for incoming URLs via `Linking.addEventListener` (warm start) and `Linking.getInitialURL()` (cold start).  If the URL uses the `docuelevate://` scheme it is automatically rewritten to `file://` before being forwarded.  Incoming files are stored in `ShareContext` and automatically uploaded by `UploadScreen`.
 
+#### Handling "unmatched route" errors from "Open In…"
+
+iOS sometimes delivers the file path under the `docuelevate://` scheme:
+
+```
+docuelevate://private/var/mobile/Library/Mobile Documents/…/Invoice.pdf
+```
+
+expo-router strips the scheme and tries to match `/private/var/mobile/…` as an in-app route.  The catch-all `app/+not-found.tsx` intercepts this, detects the filesystem-path pattern, adds the file directly to `ShareContext`, and redirects to the Upload tab.  `UploadScreen` picks up the pending file and begins uploading automatically.  The `Linking` listener in the root layout may also fire for the same URL; `ShareContext` deduplicates by URI to prevent double uploads.
+
 **Supported iOS file types:** PDF, images (JPEG / PNG / GIF / BMP / TIFF / WebP), plain text, Word (`.docx`, `.doc`), Excel (`.xlsx`, `.xls`), PowerPoint (`.pptx`, `.ppt`), and any other file (`public.data`).
 
 To use the share sheet:
@@ -174,6 +184,10 @@ To use the share sheet:
 
 > **Note:** `CFBundleDocumentTypes` with `LSHandlerRank: Alternate` means DocuElevate appears in the share sheet as an option but does **not** become the default app for any file type.
 
+#### iOS Action Extension (future enhancement)
+
+Apps like DeepL ("Translate in DeepL") appear as **Action Extensions** in the iOS share sheet, which requires a separate Xcode target and native Swift code.  This is planned as a future enhancement.  The current `CFBundleDocumentTypes` approach places DocuElevate in the "Open With" row of the share sheet.
+
 ### Android – how it works
 
 `app.json` declares `intentFilters` for `ACTION_SEND` and `ACTION_SEND_MULTIPLE` with `mimeType: "*/*"`.  When a user shares a file from another app and selects DocuElevate, Android delivers the content URI through the share intent, which is captured via `Linking.getInitialURL()` and processed the same way as on iOS.