Function immutable

Creates an immutable deep clone.

Values are processed according to their type:

• Cloned and frozen: plain objects and arrays; nested structures are cloned recursively; accessor properties are preserved as read-only (getters only, setters removed)
• Returned as-is: primitives, functions, and non-plain objects (for example, Date, Map, Set, class instances, or objects with null prototype)

This function is idempotent: calling it multiple times on the same value returns the same reference after the first call, making it safe and efficient to use defensively.

Creates an immutable deep clone, validating against a type guard.

Values are processed according to their type:

• Cloned and frozen: plain objects and arrays; nested structures are cloned recursively; accessor properties are preserved as read-only (getters only, setters removed)
• Returned as-is: primitives, functions, and non-plain objects (for example, Date, Map, Set, class instances, or objects with null prototype)

Validates value against the guard before freezing:

• Plain objects and arrays: memoizes validation; subsequent calls with the same guard skip re-validation and return the same reference; calls with a different guard trigger revalidation and rebranding
• Other values: validated on every call