chore: initialize monorepo with project scaffolding, configs, and CI setup

apps/explorer-web/src/components/siteHeader.ts

@@ -0,0 +1,20 @@
+export function siteHeader(title: string): string {
+  return `
+    <header class="site-header">
+      <div class="site-header__inner">
+        <a class="site-header__brand" href="/">AITBC Explorer</a>
+        <h1 class="site-header__title">${title}</h1>
+        <div class="site-header__controls">
+          <div data-role="data-mode-toggle"></div>
+        </div>
+        <nav class="site-header__nav">
+          <a href="/">Overview</a>
+          <a href="/blocks">Blocks</a>
+          <a href="/transactions">Transactions</a>
+          <a href="/addresses">Addresses</a>
+          <a href="/receipts">Receipts</a>
+        </nav>
+      </div>
+    </header>
+  `;
+}