v1.0.25: multi-select files, unified notification, dark theme, icon redesign

- FilesScreen: long-press enters selection mode, bulk share/delete toolbar, BackHandler
- FilesViewModel: ShareMultiple action, isSelectionMode/selectedCount state, download-to-cache for open/share
- FileWatchService: recursive FileObserver per subdirectory; unified notification updated with sync result via WorkManager flow observation
- SyncWorker: silent flag suppresses notifications when triggered by watcher; emits KEY_RESULT_SUMMARY output data
- Passbolt-inspired dark theme (Red700/Red500 primary, near-black surface)
- App icon: circular AutoSync-style sync arrows (cyan gradient, deep navy background)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/src/main/kotlin/com/syncflow/ui/files/FilesViewModel.kt

@@ -14,6 +14,7 @@ import dagger.hilt.android.qualifiers.ApplicationContext
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.*
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.flow.update
 import timber.log.Timber
 import java.io.File
 import javax.inject.Inject
@@ -21,6 +22,7 @@ import javax.inject.Inject
 sealed class FileAction {
     data class Open(val file: File) : FileAction()
     data class Share(val file: File) : FileAction()
+    data class ShareMultiple(val files: List<File>) : FileAction()
     data class Error(val message: String) : FileAction()
 }
 
@@ -57,6 +59,12 @@ class FilesViewModel @Inject constructor(
     private val _isDownloading = MutableStateFlow(false)
     val isDownloading: StateFlow<Boolean> = _isDownloading
 
+    private val _selectedKeys = MutableStateFlow<Set<String>>(emptySet())
+    val isSelectionMode: StateFlow<Boolean> = _selectedKeys.map { it.isNotEmpty() }
+        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), false)
+    val selectedCount: StateFlow<Int> = _selectedKeys.map { it.size }
+        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), 0)
+
     fun selectPair(id: Long) { _selectedPairId.value = id }
 
     fun openFile(file: SyncFileStateEntity) {
@@ -108,6 +116,44 @@ class FilesViewModel @Inject constructor(
         }
     }
 
+    fun isSelected(file: SyncFileStateEntity): Boolean = fileKey(file) in _selectedKeys.value
+
+    fun toggleSelection(file: SyncFileStateEntity) {
+        val key = fileKey(file)
+        _selectedKeys.update { if (key in it) it - key else it + key }
+    }
+
+    fun clearSelection() { _selectedKeys.value = emptySet() }
+
+    fun deleteSelected() {
+        viewModelScope.launch {
+            val toDelete = files.value.filter { isSelected(it) }
+            toDelete.forEach { file ->
+                try {
+                    resolveFile(file, emitErrorIfMissing = false)?.delete()
+                    fileStateDao.delete(file.syncPairId, file.relativePath)
+                } catch (e: Exception) {
+                    Timber.e(e, "Bulk delete failed: ${file.relativePath}")
+                }
+            }
+            clearSelection()
+        }
+    }
+
+    fun shareSelected() {
+        viewModelScope.launch {
+            val toShare = files.value.filter { isSelected(it) }
+            val resolved = toShare.mapNotNull { resolveFile(it, emitErrorIfMissing = false) }
+            if (resolved.isEmpty()) {
+                _fileAction.emit(FileAction.Error("No local files available to share"))
+                return@launch
+            }
+            _fileAction.emit(FileAction.ShareMultiple(resolved))
+        }
+    }
+
+    private fun fileKey(file: SyncFileStateEntity) = "${file.syncPairId}:${file.relativePath}"
+
     // ── Download-then-open/share ──────────────────────────────────────────────
 
     private fun downloadAndOpen(file: SyncFileStateEntity) {