feat(folio): add screen root contentDescription for scoped ax selection

Each screen root gets semantics { contentDescription = "ScreenName" } so
sanderling specs can scope element lookups through the screen: desc:LoginScreen > desc:login_submit.

examples/folio/composeApp/src/commonMain/kotlin/app/folio/feature/account/AddAccountScreen.kt

@@ -14,6 +14,8 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.semantics.contentDescription
+import androidx.compose.ui.semantics.semantics
 import androidx.compose.ui.unit.dp
 import app.folio.data.Repository
 import app.folio.navigation.Navigator
@@ -60,7 +62,7 @@ fun AddAccountScreen() {
     }
 
     Screen(
-        modifier = Modifier.testTag("AddAccountScreen"),
+        modifier = Modifier.testTag("AddAccountScreen").semantics { contentDescription = "AddAccountScreen" },
         header = {
             Header(title = "New account", left = { BackButton(onClick = { Navigator.back(Route.Home) }) })
         },

examples/folio/composeApp/src/commonMain/kotlin/app/folio/feature/auth/LoginScreen.kt

@@ -16,6 +16,8 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.semantics.contentDescription
+import androidx.compose.ui.semantics.semantics
 import androidx.compose.ui.text.input.KeyboardType
 import androidx.compose.ui.unit.dp
 import app.folio.data.Repository
@@ -60,7 +62,7 @@ fun LoginScreen(onLoggedIn: (String) -> Unit) {
         onLoggedIn(user)
     }
 
-    Screen(modifier = Modifier.testTag("LoginScreen")) {
+    Screen(modifier = Modifier.testTag("LoginScreen").semantics { contentDescription = "LoginScreen" }) {
         Spacer(Modifier.height(16.dp))
         Column(
             modifier = Modifier.fillMaxWidth().padding(vertical = 8.dp),

examples/folio/composeApp/src/commonMain/kotlin/app/folio/feature/home/HomeScreen.kt

@@ -50,7 +50,7 @@ fun HomeScreen(user: String, onLogout: () -> Unit) {
     val total = balanceOf(txns)
 
     Screen(
-        modifier = Modifier.testTag("HomeScreen"),
+        modifier = Modifier.testTag("HomeScreen").semantics { contentDescription = "HomeScreen" },
         header = {
             Header(
                 title = "Accounts",

examples/folio/composeApp/src/commonMain/kotlin/app/folio/feature/ledger/AddTransactionScreen.kt

@@ -13,6 +13,8 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.semantics.contentDescription
+import androidx.compose.ui.semantics.semantics
 import androidx.compose.ui.text.input.KeyboardType
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
@@ -91,7 +93,7 @@ fun AddTransactionScreen(accountId: String) {
     }
 
     Screen(
-        modifier = Modifier.testTag("AddTransactionScreen"),
+        modifier = Modifier.testTag("AddTransactionScreen").semantics { contentDescription = "AddTransactionScreen" },
         header = {
             Header(
                 title = "Add transaction",

examples/folio/composeApp/src/commonMain/kotlin/app/folio/feature/ledger/LedgerScreen.kt

@@ -75,7 +75,7 @@ fun LedgerScreen(accountId: String) {
     val balance = balanceOf(txns)
 
     Screen(
-        modifier = Modifier.testTag("LedgerScreen"),
+        modifier = Modifier.testTag("LedgerScreen").semantics { contentDescription = "LedgerScreen" },
         header = {
             Header(
                 title = account.name,