docs(highlight): overhaul syntax highlighting grammar and color palette

Rewrite radon-highlight.js and extra.css to use the same token color
palette as radon-project.github.io and the Radon REPL terminal.

radon-highlight.js:
- Inject !important CSS overrides at runtime to beat Material for MkDocs'
  bundled hljs theme rules, which override standard class names (.hljs-keyword,
  .hljs-string, .hljs-number, .hljs-comment, .hljs-operator) at higher cascade
  order. Non-standard names (.hljs-builtin, .hljs-fncall, .hljs-special,
  .hljs-punctuation) do not need !important.
- Rewrite grammar rule order (first-match wins): multi-line comment (#! … !#)
  → single-line comment (#) → string → builtin → keyword → number → special
  → fncall → operator → punctuation.
- Add multi-line comment rule (#! … !#) before single-line so #! is not
  consumed by the # rule.
- Expand keyword list from 6 to 30+ keywords sourced from core/tokens.py
  KEYWORDS list. Add 'as', 'elif', 'for', 'while', 'return', 'import',
  'from', 'in', 'and', 'or', 'not', 'try', 'catch', 'raise', 'break',
  'continue', 'const', 'static', 'assert', 'switch', 'case', 'default',
  'fallthrough', 'fallout', 'del', 'step', 'to'. Remove invalid 'end'.
  Add 'null', 'true', 'false', 'this', '__constructor__' as keyword-like.
- Add builtin class sourced from create_global_symbol_table() in
  core/builtin_funcs.py. Includes all 37 built-in functions plus 5 built-in
  classes: File, String, Json, Requests, builtins.
- Add fncall rule using lookahead (?=\s*\() so ( stays outside the span
  and falls through to punctuation.
- Add punctuation rule for {}()[],.;:
- Expand operator regex to cover multi-char operators (->, ++, --, ==, !=,
  <=, >=, +=, -=, *=, /=, %=) before single-char to prevent partial matches.
- Fix number regex to also match floats (\b\d+(?:\.\d+)?\b).
- Remove invalid hljs.IMMEDIATE_RE reference from string rule.
- Replace hljs.highlightAll() with explicit querySelectorAll targeting
  .language-text.highlight pre code blocks (MkDocs Pygments TextLexer
  fallback when no 'rn' lexer is registered) and re-highlight them as 'rn'
  using block.textContent to strip Pygments line-number anchors.

extra.css:
- Replace all token colors with the new palette matching radon-project.github.io.
- Add !important on .hljs-keyword, .hljs-string, .hljs-number, .hljs-comment,
  .hljs-operator as a CSS fallback matching the runtime JS injection.
- Add new rules: .hljs-builtin (#34d399), .hljs-punctuation (#94a3b8).
- Remove .hljs-function (replaced by .hljs-fncall + .hljs-special, both #c084fc).
- Set .hljs-identifier to inherit (no coloring for plain identifiers).

Token palette:
  keyword     #7dd3fc  sky-blue   bold
  builtin     #34d399  emerald
  string      #a3e635  lime-green
  number      #fb923c  orange
  operator    #f87171  salmon
  punctuation #94a3b8  slate-gray
  comment     #5c6591  slate-purple  italic
  fncall      #c084fc  violet
  special     #c084fc  violet

Author: Almas-Ali

docs/assets/radon-highlight.js

@@ -2,59 +2,96 @@ var script1 = document.createElement('script');
 script1.src = 'https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.4.0/highlight.min.js';
 script1.defer = true;
 script1.onload = function () {
+    // Inject Radon color palette with !important to beat Material theme's
+    // bundled hljs CSS which overrides standard class names (keyword, number,
+    // operator). Non-standard names (builtin, fncall, special) don't need it.
+    var rnStyle = document.createElement('style');
+    rnStyle.textContent =
+        '.hljs-keyword    { color: #7dd3fc !important; font-weight: 600; }\n' +
+        '.hljs-string     { color: #a3e635 !important; }\n' +
+        '.hljs-number     { color: #fb923c !important; }\n' +
+        '.hljs-comment    { color: #5c6591 !important; font-style: italic; }\n' +
+        '.hljs-operator   { color: #f87171 !important; }\n' +
+        '.hljs-builtin    { color: #34d399; }\n' +
+        '.hljs-special    { color: #c084fc; }\n' +
+        '.hljs-fncall     { color: #c084fc; }\n' +
+        '.hljs-punctuation{ color: #94a3b8; }\n';
+    document.head.appendChild(rnStyle);
+
     hljs.registerLanguage('rn', function (hljs) {
         return {
             contains: [
+                // Multi-line comment FIRST — #! ... !#
+                // Must come before single-line so #! isn't consumed by the # rule
                 {
-                    className: 'keyword',
-                    begin: '\\b(class|fun|if|else|true|false|null)\\b'
+                    className: 'comment',
+                    begin: '#!',
+                    end: '!#'
                 },
+                // Single-line comment — # to end of line
                 {
-                    className: 'string',
-                    begin: '"', end: '"',
-                    contains: [
-                        {
-                            className: 'escape',
-                            begin: '\\\\.', end: hljs.IMMEDIATE_RE
-                        }
-                    ]
+                    className: 'comment',
+                    begin: '#',
+                    end: '$'
                 },
+                // Strings second — protect their content from keyword matches
                 {
-                    className: 'number',
-                    begin: '\\b\\d+\\b'
+                    className: 'string',
+                    begin: '"',
+                    end: '"',
+                    contains: [{ begin: '\\\\.' }]
                 },
+                // Builtins before keywords so e.g. "str", "int" don't hit keyword
+                // Source: create_global_symbol_table() in core/builtin_funcs.py
                 {
-                    className: 'special',
-                    begin: '(?<=\\b(?:class|import|fun)\\s+)\\w+'
+                    className: 'builtin',
+                    begin: '\\b(print|print_ret|input|input_int|clear|cls|require|exit|len|is_num|is_int|is_float|is_str|is_bool|is_array|is_fun|is_null|arr_append|arr_pop|arr_extend|arr_len|arr_chunk|arr_get|str_len|str_find|str_get|int|float|str|bool|type|pyapi|time_now|license|credits|copyright|help|dir|File|String|Json|Requests|builtins)\\b'
                 },
                 {
-                    className: 'special',
-                    begin: '\_\_constructor\_\_|this'
+                    className: 'keyword',
+                    begin: '\\b(var|fun|class|if|elif|else|for|while|return|import|from|in|as|and|or|not|null|true|false|this|__constructor__|break|continue|try|catch|raise|step|to|const|static|assert|switch|case|default|fallthrough|fallout|del)\\b'
                 },
                 {
-                    className: 'fncall',
-                    begin: '(?<=\\b)(\\w+)\\s*\\('
+                    className: 'number',
+                    begin: '\\b\\d+(?:\\.\\d+)?\\b'
                 },
+                // Name immediately after class/import/fun keyword
                 {
-                    className: 'fncall',
-                    begin: '(\\)|\\()'
+                    className: 'special',
+                    begin: '(?<=\\b(?:class|import|fun)\\s+)\\w+'
                 },
+                // Function calls — lookahead so the ( stays outside the span
                 {
-                    className: 'comment',
-                    begin: '#',
-                    end: '\\n'
+                    className: 'fncall',
+                    begin: '\\b\\w+(?=\\s*\\()'
                 },
+                // Multi-char operators before single-char to avoid partial matches
                 {
-                    className: 'identifier',
-                    begin: '(\\w+)'
+                    className: 'operator',
+                    begin: '->|\\+\\+|--|==|!=|<=|>=|-=|\\+=|\\*=|/=|%=|[+\\-*/%^=<>!]'
                 },
                 {
-                    className: 'operator',
-                    begin: '(\\+|-|=|!|not|and\\^)'
+                    className: 'punctuation',
+                    begin: '[{}()\\[\\],.;:]'
                 }
             ]
         };
     });
-    hljs.highlightAll();
+
+    // MkDocs Pygments has no 'rn' lexer — falls back to TextLexer, producing
+    // <div class="language-text highlight"><pre><code>…</code></pre>.
+    // Explicitly highlight those blocks as 'rn'.
+    hljs.configure({ ignoreUnescapedHTML: true });
+
+    document.querySelectorAll(
+        '.language-text.highlight pre code, pre code.language-rn'
+    ).forEach(function (block) {
+        var result = hljs.highlight(block.textContent, {
+            language: 'rn',
+            ignoreIllegals: true
+        });
+        block.innerHTML = result.value;
+        block.classList.add('hljs');
+    });
 };
 document.head.appendChild(script1);

docs/stylesheets/extra.css

@@ -1,43 +1,44 @@
+/* Radon syntax highlight palette — mirrors radon-project.github.io token colors */
+/* !important needed on standard hljs class names to beat Material theme's bundled hljs CSS */
 .hljs-keyword {
-    color: #007acc;
-    /* Brighter shade for keywords */
-    font-style: italic;
+    color: #7dd3fc !important;
+    font-weight: 600;
 }
 
 .hljs-string {
-    color: #d14;
+    color: #a3e635 !important;
 }
 
 .hljs-number {
-    color: #c92c2c;
+    color: #fb923c !important;
 }
 
 .hljs-comment {
-    color: #6a737d;
-    /* Softer gray for comments */
+    color: #5c6591 !important;
     font-style: italic;
 }
 
-.hljs-function {
-    color: #795da3;
-    font-weight: bold;
+.hljs-operator {
+    color: #f87171 !important;
 }
 
-.hljs-identifier {
-    color: #2a7bde;
+.hljs-function,
+.hljs-special {
+    color: #c084fc;
 }
 
-.hljs-operator {
-    color: #8b7f7f;
-    font-weight: bold;
+.hljs-builtin {
+    color: #34d399;
 }
 
-.hljs-special {
-    color: rgb(255, 187, 0);
-    font-weight: bold;
+.hljs-identifier {
+    color: inherit;
+}
+
+.hljs-punctuation {
+    color: #94a3b8;
 }
 
 .hljs-fncall {
-    color: #1c92d2;
-    font-weight: bold;
+    color: #c084fc;
 }