refactor: Cleanup git state - commit all staged changes

Major refactoring cleanup:
- Add new controller architecture (class-controller-*.php)
- Add new settings-v2 UI (views/settings-v2/)
- Add new CSS architecture (agentic-sidebar.css, tokens)
- Add esbuild build pipeline (scripts/build.js, package.json)
- Add composer dependencies (vendor/)
- Add frontend src directory (assets/js/src/index.jsx)
- Add documentation files
- Remove old/obsolete files (class-settings.php, old CSS)

This commits all pending changes from previous refactoring efforts.

vendor/phpdocumentor/reflection/docs/expressions.rst

@@ -0,0 +1,60 @@
+Expressions
+===========
+
+Starting with version 5.4, we now support parsing expressions and extracting types and references to elements from them.
+
+.. info::
+
+   An expression is, for example, the default value for a property or argument, the definition of an enum case or a
+   constant value. These are called expressions and can contain more complex combinations of operators and values.
+
+As this library revolves around reflecting Static information, most parts of an expression are considered irrelevant;
+except for type information -such as type hints- and references to other elements, such as constants. As such, whenever
+an expression is interpreted, it will result in a string containing placeholders and an array containing the reflected
+parts -such as FQSENs-.
+
+This means that the getters like ``getDefault()`` will return a string or when you provide the optional argument
+$isString as being false, it will return an Expression object; which, when cast to string, will provide the same result.
+
+.. warning::
+
+   Deprecation: In version 6, we will remove the optional argument and always return an Expression object. When the
+   result was used as a string nothing will change, but code that checks if the output is a string will no longer
+   function starting from that version.
+
+This will allow consumers to be able to extract types and links to elements from expressions. This allows consumers to,
+for example, interpret the default value for a constructor promoted properties when it directly instantiates an object.
+
+Creating expressions
+--------------------
+
+.. hint::
+
+   The description below is only for internal usage and to understand how expressions work, this library deals with
+   this by default.
+
+In this library, we use the ExpressionPrinter to convert a PHP-Parser node -or expression- into an expression
+like this::
+
+     $printer = new ExpressionPrinter();
+     $expressionTemplate = $printer->prettyPrintExpr($phpParserNode);
+     $expression = new Expression($expressionTemplate, $printer->getParts());
+
+In the example above we assume that there is a PHP-Parser node representing an expression; this node is passed to the
+ExpressionPrinter -which is an adapted PrettyPrinter from PHP-Parser- which will render the expression as a readable
+template string containing placeholders, and a list of parts that can slot into the placeholders.
+
+Consuming expressions
+---------------------
+
+When using this library, you can consume these expression objects either by
+
+1. Directly casting them to a string - this will replace all placeholders with the stringified version of the parts
+2. Use the render function - this will do the same as the previous methods but you can specify one or more overrides
+   for the placeholders in the expression
+
+The second method can be used to create your own string values from the given parts and render, for example, links in
+these locations.
+
+Another way to use these expressions is to interpret the parts array, and through that way know which elements and
+types are referred to in that expression.