fix(search): clear on reopen and centre messages above the keyboard

The search ViewModel is activity-scoped and outlives the overlay, so a reopened
search showed the previous query/results — reset the query when the screen
re-enters (peeking a result keeps it, as the screen stays composed under the
detail). Add imePadding so the idle/empty message re-centres in the area above
the keyboard instead of staying centred on the full page behind it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/src/main/java/de/jeanlucmakiola/calendula/ui/search/SearchScreen.kt

@@ -11,6 +11,7 @@ import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.imePadding
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.lazy.LazyColumn
@@ -78,8 +79,12 @@ fun SearchScreen(
     val focusRequester = remember { FocusRequester() }
     val keyboard = LocalSoftwareKeyboardController.current
 
-    // Open straight into typing — request focus and raise the keyboard once.
+    // Each fresh open starts blank and straight into typing. The ViewModel is
+    // activity-scoped so it outlives the overlay; clearing on (re)enter is what
+    // resets a previous search. Peeking a result doesn't re-run this (the screen
+    // stays composed under the detail), so backing out keeps the query.
     LaunchedEffect(Unit) {
+        viewModel.setQuery("")
         focusRequester.requestFocus()
         keyboard?.show()
     }
@@ -126,7 +131,15 @@ fun SearchScreen(
             )
         },
     ) { padding ->
-        Box(modifier = Modifier.fillMaxSize().padding(padding)) {
+        // imePadding shrinks the content by the keyboard, so the centered
+        // idle/empty message re-centres in the space above it (and the results
+        // list lifts clear of the keyboard too).
+        Box(
+            modifier = Modifier
+                .fillMaxSize()
+                .padding(padding)
+                .imePadding(),
+        ) {
             when (val s = state) {
                 SearchUiState.Idle -> SearchMessage(
                     icon = null,