Fix: Position status cards at the bottom of the screen

The "Command Status" and "Detected Commands" cards were
incorrectly appearing in the middle of the screen.

This commit modifies the main `Column` within `PhotoReasoningScreen.kt`
by adding `Modifier.fillMaxHeight()`. This ensures that the main
Column expands to the full available height, allowing the
`LazyColumn` for chat messages (with `Modifier.weight(1f)`)
to correctly push the status cards to the bottom of the screen,
below the chat and user input field.

Author: google-labs-jules[bot]

app/src/main/kotlin/com/google/ai/sample/feature/multimodal/PhotoReasoningScreen.kt

@@ -273,7 +273,7 @@ fun PhotoReasoningScreen(
         }
     }
 
-    Column(modifier = Modifier.padding(all = 16.dp)) {
+    Column(modifier = Modifier.padding(all = 16.dp).fillMaxHeight()) {
         Card(
             modifier = Modifier.fillMaxWidth().padding(bottom = 16.dp),
             colors = CardDefaults.cardColors(containerColor = MaterialTheme.colorScheme.primaryContainer)