Enhance README documentation and extend CustomSystemHelper test coverage

[marevol]

This PR improves the project in the following ways:

• Expanded README.md with detailed usage instructions, supported UI components, installation and development guide, contributing guidelines, and badges for Maven Central and license.
• Added JavaDoc comments to CustomSystemHelper class for better maintainability and clarity.
• Extended CustomSystemHelperTest with multiple new test cases to cover:
• Valid, null, and invalid paths for parseProjectProperties()
• Repeated calls and thread-safety scenarios
• Logger configuration and inheritance checks
• Property persistence and behavior under different conditions

These enhancements aim to improve documentation quality and ensure robust unit test coverage for core helper logic.

[Copilot]

Pull Request Overview

This PR enhances the project's documentation and test coverage by expanding the README with comprehensive usage instructions, badges, and development guidelines, while adding extensive unit tests for the CustomSystemHelper class to improve code reliability.

Key changes include:

• Transformed README from minimal content to comprehensive documentation with installation, usage, and development guides
• Added JavaDoc comments to CustomSystemHelper for better code documentation
• Extended test coverage with 9 new test cases covering edge cases, thread safety, and property persistence scenarios

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
README.md	Complete documentation overhaul with detailed usage instructions, supported components, installation guide, and project structure
CustomSystemHelper.java	Added comprehensive JavaDoc comments and constructor documentation
CustomSystemHelperTest.java	Added extensive test coverage with edge cases, thread safety, and property validation tests

Comments suppressed due to low confidence (1)

src/test/java/org/codelibs/fess/plugin/webapp/helper/CustomSystemHelperTest.java:148

• [nitpick] This test verifies logger configuration exists but doesn't test any actual logging behavior of the CustomSystemHelper class. Consider testing actual logging functionality or remove this test if it doesn't verify meaningful behavior.

        LoggerContext context = (LoggerContext) LogManager.getContext(false);

[Copilot]

Using instanceof for inheritance testing is fragile and not recommended for unit tests. Consider testing actual behavior instead of class hierarchy, or use reflection-based assertions if inheritance verification is necessary.

Suggested change

	CustomSystemHelper helper = new CustomSystemHelper();
	// Then
	assertTrue("CustomSystemHelper should extend SystemHelper", helper instanceof org.codelibs.fess.helper.SystemHelper);
	Class<?> clazz = CustomSystemHelper.class;
	// Then
	assertEquals("CustomSystemHelper should extend SystemHelper", org.codelibs.fess.helper.SystemHelper.class, clazz.getSuperclass());

[Copilot]

Clearing system properties in tests can affect other tests running in parallel. Consider using a proper test isolation mechanism or ensuring proper cleanup in tearDown method to avoid test interdependencies.

Suggested change

	System.clearProperty("fess.webapp.plugin");
	// When
	helper1.parseProjectProperties(null);
	String propertyAfterFirst = System.getProperty("fess.webapp.plugin");
	helper2.parseProjectProperties(null);
	String propertyAfterSecond = System.getProperty("fess.webapp.plugin");
	// Then
	assertEquals("true", propertyAfterFirst);
	assertEquals("true", propertyAfterSecond);
	assertEquals("Property should remain consistent", propertyAfterFirst, propertyAfterSecond);
	String originalProperty = System.getProperty("fess.webapp.plugin");
	try {
	System.clearProperty("fess.webapp.plugin");
	// When
	helper1.parseProjectProperties(null);
	String propertyAfterFirst = System.getProperty("fess.webapp.plugin");
	helper2.parseProjectProperties(null);
	String propertyAfterSecond = System.getProperty("fess.webapp.plugin");
	// Then
	assertEquals("true", propertyAfterFirst);
	assertEquals("true", propertyAfterSecond);
	assertEquals("Property should remain consistent", propertyAfterFirst, propertyAfterSecond);
	} finally {
	if (originalProperty != null) {
	System.setProperty("fess.webapp.plugin", originalProperty);
	} else {
	System.clearProperty("fess.webapp.plugin");
	}
	}

[Copilot]

The constructor documentation states it 'Initializes the custom system helper with webapp plugin capabilities' but the constructor only calls super(). The actual webapp plugin initialization happens elsewhere, making this documentation misleading.

Suggested change

	* Initializes the custom system helper with webapp plugin capabilities.
	* Calls the parent constructor. Webapp plugin capabilities are initialized
	* during project properties parsing in the parseProjectProperties method.