add JavaFX demo application

- Add FxMain as JavaFX application entry with IOC integration
- Add FxConfig with @Bean factory methods for DateTimeFormatter
- Add MainController with constructor injection
- Add UserService and MessageService layers
- Add main.fxml view with user management UI
- Add javafx-fxml dependency and javafx-maven-plugin
- Add demo documentation and run script
- Demonstrate @Controller, @Service, @Qualifier, @PostConstruct in JavaFX context

Run with: mvn javafx:run or run-javafx-demo.bat

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

pom.xml

@@ -33,5 +33,24 @@
 			<version>${javafx.version}</version>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.openjfx</groupId>
+			<artifactId>javafx-fxml</artifactId>
+			<version>${javafx.version}</version>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.openjfx</groupId>
+				<artifactId>javafx-maven-plugin</artifactId>
+				<version>0.0.8</version>
+				<configuration>
+					<mainClass>com.imyeyu.inject.javafxdemo.FxMain</mainClass>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
 </project>