feat(search): full-text event search from the top bar

A magnifier in each calendar screen's top bar opens a search overlay: type a
query and matching events (title, location or description) appear, nearest-to-
today first; tapping a result opens its detail.

- Data: query the Events table directly with a LIKE selection on title /
  description / location (wildcards escaped), so search is unbounded in time and
  filtered provider-side. New SearchProjection + toSearchResult mapper reuse the
  .ics export's DURATION handling for recurring masters. Hidden calendars are
  filtered out, mirroring instances().
- SearchViewModel debounces the query (250 ms), needs >= 2 chars, and orders
  results upcoming-ascending then past-descending.
- SearchScreen: autofocused inline field in the top bar, GroupedRow results
  reusing the agenda row style, idle/empty states. Hosted as a CalendarHost
  overlay below detail/edit so a tapped result's detail draws on top.

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

app/src/main/java/de/jeanlucmakiola/calendula/ui/CalendarHost.kt

@@ -26,6 +26,7 @@ import de.jeanlucmakiola.calendula.ui.detail.EventDetailScreen
 import de.jeanlucmakiola.calendula.ui.edit.EventEditScreen
 import de.jeanlucmakiola.calendula.ui.imports.ImportScreen
 import de.jeanlucmakiola.calendula.ui.month.MonthScreen
+import de.jeanlucmakiola.calendula.ui.search.SearchScreen
 import de.jeanlucmakiola.calendula.ui.settings.SettingsScreen
 import de.jeanlucmakiola.calendula.ui.week.WeekScreen
 import kotlinx.datetime.LocalDate
@@ -97,6 +98,12 @@ fun CalendarHost(
     var showSettings by rememberSaveable { mutableStateOf(false) }
     val onOpenSettings = { showSettings = true }
 
+    // Full-text search — its own overlay, opened from each calendar screen's
+    // top bar. Sits below the detail/edit overlays so tapping a result reveals
+    // the detail on top and backing out returns to the results.
+    var showSearch by rememberSaveable { mutableStateOf(false) }
+    val onOpenSearch = { showSearch = true }
+
     // Calendar manager (reached from Settings) — its own overlay so it slides
     // over Settings and survives view switches.
     var showCalendars by rememberSaveable { mutableStateOf(false) }
@@ -168,6 +175,7 @@ fun CalendarHost(
                 onSelectView = onSelectView,
                 onEventClick = onEventClick,
                 onOpenSettings = onOpenSettings,
+                onOpenSearch = onOpenSearch,
                 onCreateEvent = onCreateEvent,
             )
             CalendarView.Day -> DayScreen(
@@ -175,6 +183,7 @@ fun CalendarHost(
                 onSelectView = onSelectView,
                 onEventClick = onEventClick,
                 onOpenSettings = onOpenSettings,
+                onOpenSearch = onOpenSearch,
                 onCreateEvent = onCreateEvent,
                 initialDateIso = pendingDayIso,
             )
@@ -183,6 +192,7 @@ fun CalendarHost(
                 onSelectView = onSelectView,
                 onOpenDay = onOpenDay,
                 onOpenSettings = onOpenSettings,
+                onOpenSearch = onOpenSearch,
                 onCreateEvent = onCreateEvent,
             )
             CalendarView.Agenda -> AgendaScreen(
@@ -190,10 +200,24 @@ fun CalendarHost(
                 onSelectView = onSelectView,
                 onEventClick = onEventClick,
                 onOpenSettings = onOpenSettings,
+                onOpenSearch = onOpenSearch,
                 onCreateEvent = onCreateEvent,
             )
         }
 
+        // Search overlay — below detail/edit in the Box so a tapped result's
+        // detail screen draws on top, and closing it returns to the results.
+        AnimatedVisibility(
+            visible = showSearch,
+            enter = slideInHorizontally(slideSpec) { it } + fadeIn(),
+            exit = slideOutHorizontally(slideSpec) { it } + fadeOut(),
+        ) {
+            SearchScreen(
+                onBack = { showSearch = false },
+                onEventClick = onEventClick,
+            )
+        }
+
         // Prefer the live key; fall back to the held one only while sliding out.
         val activeKey = detailKey ?: heldKey
         AnimatedVisibility(