Add KTL AI instruction guide for architecture and conventions

[Copilot]

A comprehensive agent guide was requested to document KTL class structure and coding conventions, including JS conversion rules, jQuery exceptions, and guidance to reuse existing KTL utilities. This PR adds that focused reference.

• New guidance doc
  • KTL_AI_Instructions.md describing KTL singleton/module patterns, keyword usage, and CSS naming/organization
• JavaScript conventions
  • vanilla JS preference with explicit jQuery exceptions for Knack/Chosen events and existing jQuery functions
  • alert/confirm replacement guidance via ktl.core.selectOption()
• Reuse and extension
  • directs new reusable logic into existing ktl.* modules and discourages new globals

Example snippet:

this.core = (function () {
    return {
        myFn() { /* ... */ }
    };
})();

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[CSWinnall]

This is just a draft happy for ammendments to be made @cortexrd