fix: Use length 65535 for WebAuthn blob columns to avoid MySQL MEDIUMBLOB promotion

65536 is 1 byte over MySQL's BLOB threshold (65535), causing Hibernate
to generate MEDIUMBLOB instead of BLOB. Also update README version to 4.2.2.

Author: devondragon

README.md

@@ -130,13 +130,13 @@ Spring Boot 4.0 brings significant changes including Spring Security 7 and requi
 <dependency>
     <groupId>com.digitalsanctuary</groupId>
     <artifactId>ds-spring-user-framework</artifactId>
-    <version>4.2.1</version>
+    <version>4.2.2</version>
 </dependency>
 ```
 
 **Gradle:**
 ```groovy
-implementation 'com.digitalsanctuary:ds-spring-user-framework:4.2.1'
+implementation 'com.digitalsanctuary:ds-spring-user-framework:4.2.2'
 ```
 
 #### Spring Boot 4.0 Key Changes
@@ -207,7 +207,7 @@ Follow these steps to get up and running with the Spring User Framework in your
 
    **Spring Boot 4.0 (Java 21+):**
    ```groovy
-   implementation 'com.digitalsanctuary:ds-spring-user-framework:4.2.1'
+   implementation 'com.digitalsanctuary:ds-spring-user-framework:4.2.2'
    ```
 
    **Spring Boot 3.5 (Java 17+):**

src/main/java/com/digitalsanctuary/spring/user/persistence/model/WebAuthnCredential.java

@@ -58,11 +58,11 @@ public class WebAuthnCredential {
 	private boolean backupState;
 
 	/** Attestation data from registration (can be several KB). */
-	@Column(name = "attestation_object", length = 65536)
+	@Column(name = "attestation_object", length = 65535)
 	private byte[] attestationObject;
 
 	/** Client data JSON from registration (can be several KB). */
-	@Column(name = "attestation_client_data_json", length = 65536)
+	@Column(name = "attestation_client_data_json", length = 65535)
 	private byte[] attestationClientDataJson;
 
 	/** Creation timestamp. */