Initial commit — SyncFlow Android file sync app

Supports WebDAV, SFTP, SFTPGo, Nextcloud, ownCloud, Google Drive,
Dropbox, and OneDrive. Credentials encrypted with Android Keystore.
Biometric app-lock, conflict resolution, and auto-sync via WorkManager.

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

app/src/main/kotlin/com/syncflow/data/providers/CloudProvider.kt

@@ -0,0 +1,31 @@
+package com.syncflow.data.providers
+
+import com.syncflow.domain.model.CloudAccount
+import com.syncflow.domain.model.RemoteFile
+import kotlinx.coroutines.flow.Flow
+import java.io.InputStream
+import java.io.OutputStream
+
+interface CloudProvider {
+    suspend fun testConnection(): Result<Unit>
+    suspend fun listFiles(remotePath: String): Result<List<RemoteFile>>
+    suspend fun uploadFile(
+        localStream: InputStream,
+        remotePath: String,
+        sizeBytes: Long,
+        onProgress: (bytesWritten: Long) -> Unit = {},
+    ): Result<RemoteFile>
+    suspend fun downloadFile(
+        remotePath: String,
+        destination: OutputStream,
+        onProgress: (bytesRead: Long) -> Unit = {},
+    ): Result<Unit>
+    suspend fun deleteFile(remotePath: String): Result<Unit>
+    suspend fun createDirectory(remotePath: String): Result<Unit>
+    suspend fun getFileMetadata(remotePath: String): Result<RemoteFile>
+    suspend fun moveFile(fromPath: String, toPath: String): Result<Unit>
+
+    companion object {
+        const val CHUNK_SIZE = 8 * 1024 * 1024L // 8 MB
+    }
+}