feat: add initial ISBD documentation and custom homepage component

- Introduced ISBD documentation structure, including sections like about, assessment, examples, glossary, introduction, and vocabularies.
- Implemented a `StandardHomePage` component with tabbed navigation (Welcome/Contents) for the ISBD homepage.
- Styled the ISBD homepage using SCSS with IFLA-themed colors.

Author: jonphipps

package.json

@@ -79,8 +79,8 @@
     "sheets:export": "ts-node scripts/sheets-export.ts",
     "sheets:import": "ts-node scripts/sheets-import.ts",
     "sheets:ingest": "node scripts/sheets-to-mdx.js --sheet 'https://docs.google.com/...'",
-    "start": "pnpm stop:portal && pnpm build:deps && DOCS_ENV=local docusaurus start",
-    "start:all": "pnpm stop:all && pnpm build:deps && concurrently \"DOCS_ENV=local docusaurus start portal --port 3000\" \"DOCS_ENV=local docusaurus start standards/ISBDM --port 3001\" \"DOCS_ENV=local docusaurus start standards/LRM --port 3002\" \"DOCS_ENV=local docusaurus start standards/FRBR --port 3003\" \"DOCS_ENV=local docusaurus start standards/isbd --port 3004\" \"DOCS_ENV=local docusaurus start standards/muldicat --port 3005\" \"DOCS_ENV=local docusaurus start standards/unimarc --port 3006\"",
+    "start": "pnpm stop:portal && pnpm build:theme && DOCS_ENV=local docusaurus start",
+    "start:all": "pnpm stop:all && pnpm build:theme && concurrently \"DOCS_ENV=local docusaurus start portal --port 3000\" \"DOCS_ENV=local docusaurus start standards/ISBDM --port 3001\" \"DOCS_ENV=local docusaurus start standards/LRM --port 3002\" \"DOCS_ENV=local docusaurus start standards/FRBR --port 3003\" \"DOCS_ENV=local docusaurus start standards/isbd --port 3004\" \"DOCS_ENV=local docusaurus start standards/muldicat --port 3005\" \"DOCS_ENV=local docusaurus start standards/unimarc --port 3006\"",
     "start:frbr": "pnpm stop:frbr && DOCS_ENV=local docusaurus start standards/FRBR --port 3003",
     "start:isbd": "pnpm stop:isbd && DOCS_ENV=local docusaurus start standards/isbd --port 3004",
     "start:isbdm": "pnpm stop:isbdm && DOCS_ENV=local docusaurus start standards/ISBDM --port 3001",

packages/theme/src/components/StandardHomePage/index.tsx

@@ -0,0 +1,98 @@
+import React, { useState } from 'react';
+import clsx from 'clsx';
+import useBaseUrl from '@docusaurus/useBaseUrl';
+import styles from './styles.module.scss';
+
+export interface StandardHomePageProps {
+  children: React.ReactNode;
+  contentsContent?: React.ReactNode;
+  frontMatter?: {
+    title?: string;
+    subtitle?: string;
+  };
+}
+
+const StandardHomePage: React.FC<StandardHomePageProps> = ({
+  children,
+  contentsContent,
+  frontMatter = {}
+}) => {
+  const [activeTab, setActiveTab] = useState<'welcome' | 'contents'>('welcome');
+
+  // Hook calls must be unconditional – compute the logo URL here once
+  const logoUrl = useBaseUrl('/img/logo-ifla_black.png');
+
+  const { title = "International Standard Bibliographic Description", subtitle } = frontMatter;
+
+  return (
+    <div className={styles.standardHomepage}>
+      {/* Tab Navigation */}
+      <div className={styles.tabNavigation}>
+        <button
+          className={clsx(styles.tabButton, {
+            [styles.tabButtonActive]: activeTab === 'welcome'
+          })}
+          onClick={() => setActiveTab('welcome')}
+          aria-selected={activeTab === 'welcome'}
+          role="tab"
+        >
+          Welcome
+        </button>
+        <button
+          className={clsx(styles.tabButton, {
+            [styles.tabButtonActive]: activeTab === 'contents'
+          })}
+          onClick={() => setActiveTab('contents')}
+          aria-selected={activeTab === 'contents'}
+          role="tab"
+        >
+          Contents
+        </button>
+      </div>
+
+      {/* Tab Content */}
+      <div className={styles.tabContent}>
+        {activeTab === 'welcome' && (
+          <div className={styles.welcomeTab} role="tabpanel" aria-labelledby="welcome-tab">
+            <div className={styles.heroSection}>
+              <div className={styles.heroContent}>
+                <div className={styles.logoContainer}>
+                  <img
+                    src={logoUrl}
+                    alt="IFLA Logo"
+                  />
+                </div>
+                <div className={styles.titleContainer}>
+                  <h1 className={styles.heroTitle}>{title}</h1>
+                  {subtitle && <p className={styles.heroSubtitle}>{subtitle}</p>}
+                </div>
+                <div className={styles.quickStats}>
+                  <div className={styles.statItem}>
+                    <span className={styles.statLabel}>Current Release</span>
+                    <span className={styles.statValue}>2024.1</span>
+                  </div>
+                </div>
+              </div>
+            </div>
+
+            <div className={styles.welcomeContent}>
+              {children}
+            </div>
+          </div>
+        )}
+
+        {activeTab === 'contents' && (
+          <div className={styles.contentsTab} role="tabpanel" aria-labelledby="contents-tab">
+            {contentsContent || (
+              <div className={styles.contentsPlaceholder}>
+                <p>Contents tab content should be provided via the contentsContent prop.</p>
+              </div>
+            )}
+          </div>
+        )}
+      </div>
+    </div>
+  );
+};
+
+export default StandardHomePage;