Improved UI and enhanced expense creation

Updated the UI across all screens (Login, Dashboard, Account Selection, Expense Details, and Creation) with a more modern, card-based design and improved layouts.

Expense creation now includes:
- Real-time split validation to ensure shares match the total amount.
- An "Equal Split" shortcut for quick allocation.
- Support for optional descriptions and multiple file attachments.
- Strict save validation.

The `MainActivity` now supports edge-to-edge display, and the `AccountDao` includes a new query to fetch accounts by ID. Added `material-icons-extended` dependency for enhanced iconography.

app/build.gradle.kts

@@ -61,6 +61,7 @@ dependencies {
 
     //Manually added
     implementation("androidx.datastore:datastore-preferences:1.2.0")
+    implementation("androidx.compose.material:material-icons-extended:1.6.0")
 
     val room_version = "2.8.4"
     implementation("androidx.room:room-runtime:$room_version")