android, desktop, ios: fix trailing dot in saved name for files without extension (#7016)

apps/ios/SimpleXChat/ImageUtils.swift

@@ -297,7 +297,7 @@ private func uniqueCombine(_ fileName: String, fullPath: Bool = false) -> String
         let name = ns.deletingPathExtension
         let ext = ns.pathExtension
         let suffix = (n == 0) ? "" : "_\(n)"
-        let f = "\(name)\(suffix).\(ext)"
+        let f = ext.isEmpty ? "\(name)\(suffix)" : "\(name)\(suffix).\(ext)"
         return (FileManager.default.fileExists(atPath: fullPath ? f : getAppFilePath(f).path)) ? tryCombine(fileName, n + 1) : f
     }
     return tryCombine(fileName, 0)

apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/views/helpers/Utils.kt

@@ -383,7 +383,7 @@ fun uniqueCombine(fileName: String, dir: File): String {
   val ext = orig.extension
   fun tryCombine(n: Int): String {
     val suffix = if (n == 0) "" else "_$n"
-    val f = "$name$suffix.$ext"
+    val f = if (ext.isEmpty()) "$name$suffix" else "$name$suffix.$ext"
     return if (File(dir, f).exists()) tryCombine(n + 1) else f
   }
   return tryCombine(0)