chore: initialize @limitless/ui git repo + add AppShell

This brings the long-untracked @limitless/ui source tree under version
control. Until now /srv/k8s/templates/limitless-ui has been a plain
file: dependency consumed by gscChronos / gscCRM / gscAdmin, with
copies scattered across web/gsc{Portal,WWW,Aether,Register}/ and
apps/gsc{Meet,Share}/. None were git-tracked.

Treating /srv/k8s/templates/limitless-ui as the canonical going
forward; secondary copies should be replaced with this version
in their consumers' Dockerfiles when they next get touched.

Changes in this initial commit beyond the snapshot:
- Add src/layout/AppShell.tsx — runtime-loaded chrome (header,
  sidebar, footer) backed by gsc-shell-api. Public surface:
    AppShell, ShellProvider, useShell, ShellConfig types
  Framework-agnostic (no Next.js dep). Apps pass appKey + apiUrl +
  getToken; AppShell composes the existing PageShell / Navbar /
  Sidebar / Footer primitives with API data.
- Re-export AppShell from src/index.ts.
- Fix build script: `tsc -p tsconfig.json --noEmit false`. The bare
  `tsc` command was a no-op because tsconfig.json sets noEmit:true
  for typecheck speed. Existing dist/ only existed because of an
  earlier emit; clean rebuilds were silently broken.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/PageHeader.tsx

@@ -0,0 +1,100 @@
+import React from 'react';
+import { Breadcrumbs, BreadcrumbItem } from './Breadcrumbs';
+
+export type PageHeaderProps = {
+  /** Page title */
+  title: React.ReactNode;
+  /** Subtitle shown after title */
+  subtitle?: React.ReactNode;
+  /** Icon before title */
+  icon?: React.ReactNode;
+  /** Breadcrumb items */
+  breadcrumbs?: BreadcrumbItem[];
+  /** Breadcrumb line actions (right side of breadcrumb line) */
+  breadcrumbActions?: React.ReactNode;
+  /** Header actions (buttons, dropdowns on right side of page title) */
+  actions?: React.ReactNode;
+  /** Additional className */
+  className?: string;
+  /** Show breadcrumb line (default true) */
+  showBreadcrumbLine?: boolean;
+};
+
+/**
+ * Layout 3 page header component.
+ *
+ * Structure:
+ * - breadcrumb-line (optional): breadcrumbs + header-elements
+ * - page-header-content: page-title + header-elements with actions
+ */
+export function PageHeader({
+  title,
+  subtitle,
+  icon,
+  breadcrumbs,
+  breadcrumbActions,
+  actions,
+  className = '',
+  showBreadcrumbLine = true
+}: PageHeaderProps) {
+  return (
+    <div className={`page-header ${className}`.trim()}>
+      {/* Breadcrumb line */}
+      {showBreadcrumbLine && breadcrumbs && (
+        <div className="breadcrumb-line breadcrumb-line-light header-elements-md-inline">
+          <div className="d-flex">
+            <Breadcrumbs items={breadcrumbs} className="mb-0" />
+            <a href="#" className="header-elements-toggle text-default d-md-none">
+              <i className="icon-more"></i>
+            </a>
+          </div>
+          {breadcrumbActions && (
+            <div className="header-elements d-none">
+              <div className="breadcrumb justify-content-center">
+                {breadcrumbActions}
+              </div>
+            </div>
+          )}
+        </div>
+      )}
+
+      {/* Page header content */}
+      <div className="page-header-content header-elements-md-inline">
+        <div className="page-title d-flex">
+          <h4>
+            {icon && <span className="me-2">{icon}</span>}
+            <span className="fw-semibold">{title}</span>
+            {subtitle && <span> - {subtitle}</span>}
+          </h4>
+          <a href="#" className="header-elements-toggle text-default d-md-none">
+            <i className="icon-more"></i>
+          </a>
+        </div>
+
+        {actions && (
+          <div className="header-elements d-none mb-3 mb-md-0">
+            {actions}
+          </div>
+        )}
+      </div>
+    </div>
+  );
+}
+
+export type BreadcrumbElementProps = {
+  icon?: React.ReactNode;
+  children: React.ReactNode;
+  href?: string;
+};
+
+/**
+ * Breadcrumb action element for page header.
+ */
+export function BreadcrumbElement({ icon, children, href = '#' }: BreadcrumbElementProps) {
+  return (
+    <a href={href} className="breadcrumb-elements-item">
+      {icon && <span className="me-2">{icon}</span>}
+      {children}
+    </a>
+  );
+}