Rename app to HSRename; use HSRename.png as icon; update build script and README

Made-with: Cursor

main.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 """
-Bulk Renamer - Native Linux GUI for mass renaming files.
+HSRename - Native Linux GUI for mass renaming files.
 Inspired by Bulk Rename Utility (Windows); supports preview and flexible rules.
 """
 import sys
@@ -21,7 +21,7 @@ def main():
         Qt.HighDpiScaleFactorRoundingPolicy.PassThrough
     )
     app = QApplication(sys.argv)
-    app.setApplicationName("Bulk Renamer")
+    app.setApplicationName("HSRename")
     win = MainWindow()
     win.show()
     sys.exit(app.exec())