fix(mobile): iOS share sheet, empty files tab, and stuck upload status

- app.json: add CFBundleDocumentTypes to iOS infoPlist so the app
  appears in the iOS Share Sheet; add ACTION_SEND/SEND_MULTIPLE
  intentFilters for Android share intent support

- src/context/ShareContext.tsx (new): React context that queues files
  received from the share sheet and delivers them to UploadScreen

- app/_layout.tsx: wrap in ShareProvider; add Linking handler
  (makeUrlHandler factory + getInitialURL cold-start + addEventListener
  warm-start) to capture file:// and content:// URLs

- src/services/api.ts: fix FileRecord interface (original_filename,
  nested ProcessingStatus, mime_type); fix UploadResponse interface;
  fix listFiles() (per_page param, unwrap data.files); add
  getFileStatus(fileId) for single-file status polling

- src/screens/FilesScreen.tsx: use file.original_filename and
  file.processing_status.status; fix statusEmoji to use actual backend
  status values (completed/pending/duplicate)

- src/screens/UploadScreen.tsx: consume ShareContext for auto-upload of
  shared files; add 5-second polling loop (search by filename → file_id
  → getFileStatus) to show real-time server processing status;
  uploadFile wrapped in useCallback; proper effect dependency arrays

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

mobile/app/_layout.tsx

@@ -4,13 +4,48 @@
  * Wraps the entire app in AuthProvider and SafeAreaProvider, then uses the
  * AuthGuard component to redirect between the unauthenticated (auth) route
  * group and the authenticated (tabs) route group based on session state.
+ *
+ * ShareProvider + Linking listener: when iOS opens the app via the share
+ * sheet (CFBundleDocumentTypes) or Android via a SEND intent, the incoming
+ * file:// / content:// URL is captured and forwarded to UploadScreen via
+ * ShareContext.
  */
 
+import * as Linking from "expo-linking";
 import { Stack, useRouter, useSegments } from "expo-router";
 import React, { useEffect } from "react";
 import { ActivityIndicator, StyleSheet, Text, View } from "react-native";
 import { SafeAreaProvider } from "react-native-safe-area-context";
 import { AuthProvider, useAuth } from "../src/context/AuthContext";
+import { ShareProvider, useShare } from "../src/context/ShareContext";
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+/** Extract a display filename from a file:// or content:// URI. */
+function filenameFromUri(uri: string): string {
+  try {
+    const decoded = decodeURIComponent(uri);
+    // Take the last path segment and strip any query string
+    const last = decoded.split("/").pop() ?? "shared_file";
+    return last.split("?")[0] || "shared_file";
+  } catch {
+    return "shared_file";
+  }
+}
+
+/**
+ * Build a Linking URL handler that forwards incoming file:// / content://
+ * URLs to ShareContext.  Extracted as a module-level factory so the handler
+ * itself is created once and can be easily unit-tested without a React context.
+ */
+function makeUrlHandler(addPendingFile: (f: { uri: string; filename: string }) => void) {
+  return ({ url }: { url: string }) => {
+    if (!url.startsWith("file://") && !url.startsWith("content://")) return;
+    addPendingFile({ uri: url, filename: filenameFromUri(url) });
+  };
+}
 
 // ---------------------------------------------------------------------------
 // Auth guard – redirects to the correct route group after auth state resolves
@@ -18,9 +53,26 @@ import { AuthProvider, useAuth } from "../src/context/AuthContext";
 
 function AuthGuard() {
   const { isLoading, isAuthenticated } = useAuth();
+  const { addPendingFile } = useShare();
   const segments = useSegments();
   const router = useRouter();
 
+  // Listen for files shared from other apps (iOS Share Sheet / Android Intent).
+  // Both cold-start (app was not running) and warm-start (app in background)
+  // cases are handled.
+  useEffect(() => {
+    const handleIncomingUrl = makeUrlHandler(addPendingFile);
+
+    // Cold start – app launched directly by a share action
+    Linking.getInitialURL().then((url) => {
+      if (url) handleIncomingUrl({ url });
+    });
+
+    // Warm start – app was already running when the share action occurred
+    const subscription = Linking.addEventListener("url", handleIncomingUrl);
+    return () => subscription.remove();
+  }, [addPendingFile]);
+
   useEffect(() => {
     if (isLoading) return;
 
@@ -59,9 +111,11 @@ function AuthGuard() {
 export default function RootLayout() {
   return (
     <SafeAreaProvider>
-      <AuthProvider>
-        <AuthGuard />
-      </AuthProvider>
+      <ShareProvider>
+        <AuthProvider>
+          <AuthGuard />
+        </AuthProvider>
+      </ShareProvider>
     </SafeAreaProvider>
   );
 }