Fix symlink creation issues and add installation verification checks for the installer scripts

install-git-credential-manager.sh

@@ -341,9 +341,16 @@ install_from_tarball() {
         cd "$extracted_dir"
         print_status "Installing binary to $INSTALL_DIR..."
         sudo install -m 755 git-credential-manager "$INSTALL_DIR/git-credential-manager"
+
+        # Verify installation
+        if [[ ! -f "$INSTALL_DIR/git-credential-manager" ]]; then
+            print_error "Failed to install Git Credential Manager binary"
+            return 1
+        fi
+
         sudo ln -sf "$INSTALL_DIR/git-credential-manager" "$INSTALL_DIR/git-credential-manager-core"
     fi
-    
+
     print_success "Binary installed successfully"
 }