v1.0.65: chunked upload for large files (>100MB) on Nextcloud

Big-file testing found single-PUT uploads 413 above the server's per-request
cap (Apache LimitRequestBody / PHP post_max_size / proxy limits). NextcloudProvider
now uploads files >chunkSize (100MB) via the dav/uploads chunked API: MKCOL a
session, PUT N chunks, then MOVE .file onto the destination (atomic assemble).
Bypasses any per-request cap so multi-GB files back up. Verified byte-exact
(multi-chunk) against live Nextcloud. SFTP already streams; single-PUT path
unchanged for <=100MB.

app/src/androidTest/kotlin/com/syncflow/NextcloudIntegrationTest.kt

@@ -13,6 +13,7 @@ import com.syncflow.domain.sync.LocalFileInfo
 import com.syncflow.domain.sync.SyncDecision
 import com.syncflow.domain.sync.syncDecide
 import kotlinx.coroutines.runBlocking
+import org.junit.Assert.assertArrayEquals
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertNotNull
 import org.junit.Assert.assertTrue
@@ -114,4 +115,27 @@ class NextcloudIntegrationTest {
             runCatching { p.deleteFile(dir) } // best-effort cleanup of the test folder
         }
     }
+
+    @Test
+    fun chunkedUpload_assemblesLargeFileByteExact() = runBlocking {
+        assumeTrue("ncUrl/ncUser/ncPass required", url != null && user != null && pass != null)
+        // Tiny chunk size exercises multi-chunk assembly without needing a multi-GB file.
+        val account = CloudAccount(
+            id = 1, displayName = "IT", email = user, providerType = ProviderType.NEXTCLOUD,
+            credentialJson = """{"username":"$user","password":"$pass"}""", serverUrl = url, port = null,
+        )
+        val p = NextcloudProvider(account, chunkSize = 1L * 1024 * 1024) // 1 MB chunks
+        val dir = "SyncFlowChunk_${System.currentTimeMillis()}"
+        try {
+            p.createDirectory(dir).getOrThrow()
+            val payload = ByteArray(5 * 1024 * 1024 + 7).also { java.util.Random(7).nextBytes(it) } // ~5 MB -> 6 chunks
+            val up = p.uploadFile(ByteArrayInputStream(payload), "$dir/big.bin", payload.size.toLong())
+            assertTrue("chunked upload failed: ${up.exceptionOrNull()}", up.isSuccess)
+            assertEquals(payload.size.toLong(), p.listFiles(dir).getOrThrow().first { it.name == "big.bin" }.sizeBytes)
+            val out = ByteArrayOutputStream(); p.downloadFile("$dir/big.bin", out).getOrThrow()
+            assertArrayEquals("chunk-assembled content must equal the original bytes", payload, out.toByteArray())
+        } finally {
+            runCatching { p.deleteFile(dir) }
+        }
+    }
 }