fix: improve file sharing on Android using app-private storage

- Replace direct file writing with app-private storage + share dialog
- Add Share plugin for cross-platform file sharing
- Update file paths configuration for Android
- Fix permission issues by using Directory.Data instead of Documents
- Simplify file export flow in DataExportSection

package-lock.json

@@ -15,6 +15,7 @@
         "@capacitor/core": "^6.2.0",
         "@capacitor/filesystem": "^6.0.0",
         "@capacitor/ios": "^6.2.0",
+        "@capacitor/share": "^6.0.3",
         "@capawesome/capacitor-file-picker": "^6.2.0",
         "@dicebear/collection": "^5.4.1",
         "@dicebear/core": "^5.4.1",
@@ -2908,6 +2909,15 @@
         "@capacitor/core": "^6.2.0"
       }
     },
+    "node_modules/@capacitor/share": {
+      "version": "6.0.3",
+      "resolved": "https://registry.npmjs.org/@capacitor/share/-/share-6.0.3.tgz",
+      "integrity": "sha512-BkNM73Ix+yxQ7fkni8CrrGcp1kSl7u+YNoPLwWKQ1MuQ5Uav0d+CT8M67ie+3dc4jASmegnzlC6tkTmFcPTLeA==",
+      "license": "MIT",
+      "peerDependencies": {
+        "@capacitor/core": "^6.0.0"
+      }
+    },
     "node_modules/@capawesome/capacitor-file-picker": {
       "version": "6.2.0",
       "resolved": "https://registry.npmjs.org/@capawesome/capacitor-file-picker/-/capacitor-file-picker-6.2.0.tgz",