Add custom QZ Tray fork with pairing key authentication

- Custom fork of QZ Tray 2.2.x with certificate validation bypassed
- Implemented pairing key (HMAC) authentication as replacement
- Modified files: PrintSocketClient.java (certificate check disabled)
- New files: PairingAuth.java, PairingConfigDialog.java
- Excluded build artifacts (out/, lib/javafx*) from repository
- Library JARs included for dependency management

tray/assets/signing/sign-message.cls

@@ -0,0 +1,54 @@
+/*
+ * Salesforce APEX Signing Example
+ * Returns the signed message to a wired controller
+ */
+
+// #########################################################
+// #             WARNING   WARNING   WARNING               #
+// #########################################################
+// #                                                       #
+// # This file is intended for demonstration purposes      #
+// # only.                                                 #
+// #                                                       #
+// # It is the SOLE responsibility of YOU, the programmer  #
+// # to prevent against unauthorized access to any signing #
+// # functions.                                            #
+// #                                                       #
+// # Organizations that do not protect against un-         #
+// # authorized signing will be black-listed to prevent    #
+// # software piracy.                                      #
+// #                                                       #
+// # -QZ Industries, LLC                                   #
+// #                                                       #
+// #########################################################
+
+public with sharing class SignMessage {
+    @AuraEnabled(cacheable = true)
+    public static String signMessage(String toSign){
+        String privateKeyBase64 = '<private-key.pem content without header or footer>';
+
+        Blob sig = Crypto.sign('RSA-SHA512',
+            Blob.valueOf(toSign),
+            EncodingUtil.base64Decode(privateKeyBase64));
+
+        return EncodingUtil.base64Encode(sig);
+    }
+}
+
+/** JavaScript - Adjust as needed
+
+import signMessage from '@salesforce/apex/SignMessage.signMessage';
+@wire(signMessage)
+
+qz.security.setSignatureAlgorithm("SHA512");
+qz.security.setSignaturePromise(function(toSign) {
+    return function (resolve, reject) {
+        try {
+            resolve(signMessage({toSign : toSign}));
+        } catch(err) {
+            reject(err);
+        }
+    }
+});
+
+**/