Add hashCode calculation to TestSuite based on loaded YAML content

[snytkine]

Description

Add a calculated hashCode to the TestSuite record that is based on the loaded YAML file content. This hashCode will be computed once when the raw YAML file is initially loaded and will serve to uniquely identify test suite configurations.

Requirements

• Calculate the hashCode from the raw YAML file content when TestSuiteLoader.load() is called
• Store as a private property in the TestSuite record
• Provide a getter method to access the hashCode
• Do NOT add this property to the YAML schema (test-suite-schema.json)
• The hashCode should be immutable once calculated (determined at load time)

Acceptance Criteria

• TestSuite record has a private hashCode field
• Getter method getFileHashCode() (or similar) returns the calculated hash
• Hash is computed from the raw YAML file content in TestSuiteLoader
• Schema file remains unchanged
• Unit tests cover hashCode calculation for different YAML contents
• Javadoc documents the hashCode field and getter method

Technical Notes

• This will be useful for caching, comparison, and detecting YAML file changes
• Consider using a standard hash function (e.g., SHA-256 or MD5)
• The hash should be deterministic for the same YAML content