feat(ics): import UI — open/receive .ics, 1-vs-many routing

Completes v2.7 Branch 2. Wires the import core into the app:

- Manifest ACTION_VIEW/SEND for text/calendar; MainActivity parses the
  incoming Uri (content/file only, so calendula:// deep-links don't match)
  and routes it through RootScreen → CalendarHost like the other one-shot
  intents.
- ImportViewModel reads + parses the file and routes by count: one event →
  the prefilled create form for review (EventEditViewModel.openImported,
  which freezes the reminder default so the file's reminders win); many →
  ImportScreen with a writable-calendar picker, then a bulk import (UID
  dedup) and a result summary.
- ImportScreen also surfaces parser warnings (skipped recurrence overrides,
  ignored attendees, unknown-timezone fallback). Strings EN+DE.

Package is ui.imports (not ui.import — Java keyword). lint + test +
assembleDebug green. No v2.7 tag until on-device review.

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

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

@@ -15,6 +15,7 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
+import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import de.jeanlucmakiola.calendula.ui.agenda.AgendaScreen
 import de.jeanlucmakiola.calendula.ui.calendars.CalendarsScreen
@@ -23,6 +24,7 @@ import de.jeanlucmakiola.calendula.ui.common.rememberCalendarSlideSpec
 import de.jeanlucmakiola.calendula.ui.day.DayScreen
 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.settings.SettingsScreen
 import de.jeanlucmakiola.calendula.ui.week.WeekScreen
@@ -48,6 +50,8 @@ fun CalendarHost(
     onDetailKeyConsumed: () -> Unit = {},
     widgetNavRequest: WidgetNavRequest? = null,
     onWidgetNavConsumed: () -> Unit = {},
+    requestedImportUri: android.net.Uri? = null,
+    onImportConsumed: () -> Unit = {},
 ) {
     var view by rememberSaveable { mutableStateOf(CalendarView.Week) }
     val onSelectView: (CalendarView) -> Unit = { view = it }
@@ -121,6 +125,18 @@ fun CalendarHost(
     var editKey by rememberSaveable { mutableStateOf<LongArray?>(null) }
     var heldEditKey by remember { mutableStateOf<LongArray?>(null) }
 
+    // An opened/received .ics file. [ImportScreen] parses it and either opens
+    // the prefilled create form (one event → [importForm]) or its own bulk
+    // picker (many). A plain conditional overlay (no slide) — it's transient.
+    var importUri by remember { mutableStateOf<android.net.Uri?>(null) }
+    var importForm by remember { mutableStateOf<EventForm?>(null) }
+    LaunchedEffect(requestedImportUri) {
+        if (requestedImportUri != null) {
+            importUri = requestedImportUri
+            onImportConsumed()
+        }
+    }
+
     // A home-screen widget launch asks to open a date (→ day view) or start a
     // create. Handled once and cleared, mirroring [requestedDetailKey].
     LaunchedEffect(widgetNavRequest) {
@@ -254,5 +270,26 @@ fun CalendarHost(
         ) {
             CalendarsScreen(onBack = { showCalendars = false })
         }
+
+        // Import flow for an opened/received .ics file. A single event routes
+        // into the create form (prefilled, for review); many open the picker.
+        importUri?.let { uri ->
+            ImportScreen(
+                uri = uri,
+                onClose = { importUri = null },
+                onOpenSingle = { form ->
+                    importUri = null
+                    importForm = form
+                },
+            )
+        }
+        importForm?.let { form ->
+            EventEditScreen(
+                initialDateIso = null,
+                initialForm = form,
+                onClose = { importForm = null },
+                onSaved = { importForm = null },
+            )
+        }
     }
 }