feat(docs): add CodeBlock with three context-aware modes

- Mode A (Terminal): bash/sh languages or wizard-glyph content
- Mode B (VS Code tab): blocks with a title attribute
- Mode C (Minimal): everything else

Component renders only structural markup; CSS for each mode is
added in the following commits.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/components/code-block.tsx

@@ -0,0 +1,110 @@
+"use client";
+
+import {
+  type ReactNode,
+  type ReactElement,
+  isValidElement,
+} from "react";
+import { CopyButton } from "./copy-button";
+
+type Props = {
+  children?: ReactNode;
+  className?: string;
+  title?: string;
+  // rehype-pretty-code adds data attributes such as data-language; capture them via index signature
+  [key: string]: unknown;
+};
+
+const TERMINAL_LANGS = new Set(["bash", "sh", "shell", "zsh"]);
+const WIZARD_GLYPHS = /^\s*[◆◇◯◐○●]/;
+
+function extractText(node: ReactNode): string {
+  if (typeof node === "string") return node;
+  if (typeof node === "number") return String(node);
+  if (Array.isArray(node)) return node.map(extractText).join("");
+  if (isValidElement(node)) {
+    const props = (node as ReactElement<{ children?: ReactNode }>).props;
+    return extractText(props.children);
+  }
+  return "";
+}
+
+function detectLanguage(props: Props, children: ReactNode): string | null {
+  const dataLang = props["data-language"];
+  if (typeof dataLang === "string" && dataLang) return dataLang;
+
+  const className = typeof props.className === "string" ? props.className : "";
+  const m = className.match(/language-([\w-]+)/);
+  if (m) return m[1];
+
+  if (isValidElement(children)) {
+    const childProps = (children as ReactElement<{ className?: string }>).props;
+    const childClass = typeof childProps.className === "string" ? childProps.className : "";
+    const cm = childClass.match(/language-([\w-]+)/);
+    if (cm) return cm[1];
+  }
+
+  return null;
+}
+
+export function CodeBlock(props: Props) {
+  const { children, title, className: _ignored, ...rest } = props;
+  const language = detectLanguage(props, children);
+  const codeText = extractText(children);
+
+  const isTerminal =
+    (language !== null && TERMINAL_LANGS.has(language)) ||
+    WIZARD_GLYPHS.test(codeText);
+  const hasTitle = typeof title === "string" && title.length > 0;
+
+  // Mode A — Terminal
+  if (isTerminal) {
+    return (
+      <div className="ktx-code ktx-code-terminal group">
+        <div className="ktx-code-terminal-head">
+          <span className="ktx-tl-dot" style={{ background: "#ff5f57" }} />
+          <span className="ktx-tl-dot" style={{ background: "#febc2e" }} />
+          <span className="ktx-tl-dot" style={{ background: "#28c840" }} />
+          <span className="ktx-code-terminal-label">
+            {hasTitle ? title : "zsh"}
+          </span>
+          <CopyButton
+            text={codeText}
+            className="ml-auto text-white/80"
+          />
+        </div>
+        <pre {...rest} className="ktx-code-body ktx-code-body-terminal">
+          {children}
+        </pre>
+      </div>
+    );
+  }
+
+  // Mode B — VS Code tab (filename present)
+  if (hasTitle) {
+    return (
+      <div className="ktx-code ktx-code-tab group">
+        <div className="ktx-code-tab-head">
+          <span className="ktx-file-glyph" data-lang={language ?? ""} />
+          <span className="ktx-code-tab-filename">{title}</span>
+          {language && <span className="ktx-lang-pill">{language}</span>}
+          <CopyButton text={codeText} className="ml-auto" />
+        </div>
+        <pre {...rest} className="ktx-code-body ktx-code-body-tab">
+          {children}
+        </pre>
+      </div>
+    );
+  }
+
+  // Mode C — Minimal default
+  return (
+    <div className="ktx-code ktx-code-minimal group relative">
+      {language && <span className="ktx-code-minimal-lang">{language}</span>}
+      <CopyButton text={codeText} className="ktx-code-minimal-copy" />
+      <pre {...rest} className="ktx-code-body ktx-code-body-minimal">
+        {children}
+      </pre>
+    </div>
+  );
+}