Send more text file types from Desktop app and improve indexing them

- Allow syncing more file types from desktop app to index on server
  - Use `file-type' package to identify valid text file types on Desktop app

- Split plaintext entries into smaller logical units than a whole file
  Since the text splitting upgrades in #645, compiled chunks have more
  logical splits like paragraph, sentence.
  Show those (potentially) smaller snippets to the user as references

- Tangential Fix:
  Initialize unbound currentTime variable for error log timestamp

src/interface/desktop/package.json

@@ -20,6 +20,7 @@
     "axios": "^1.6.4",
     "cron": "^2.4.3",
     "electron-store": "^8.1.0",
-    "fs": "^0.0.1-security"
+    "fs": "^0.0.1-security",
+    "file-type": "^16.2.0"
   }
 }