Catalog Client Script: Normalise and reset MRVS rows when a controlling variable changes - Pull 1

[hanna-g-sn]

PR Description:

Title: Catalog Client Script: Normalise and reset MRVS rows when a controlling variable changes

This adds a client-side utility for Multi Row Variable Sets that clears invalid columns, deduplicates rows by a chosen key, and sorts rows after a controlling variable changes. It improves data quality and user experience with no server round trips.

Includes: README, main script, and a simplified variant file with just column resets.

Testing: Verified on a Catalog Item with an MRVS containing columns hostname, env, owner. Changing the Environment variable resets env/owner, removes duplicates by hostname, and sorts by hostname.

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[ravichandra1998g]

looks good to me.