Add dataset library, extract-to-dataset, and render-time reference resolution

src/app/App.tsx

@@ -1,10 +1,14 @@
+import { useEffect } from 'react';
 import { ConfirmDialog } from './components/ConfirmDialog';
 import { LivePreview } from './components/LivePreview';
+import { ModalShell } from './components/ModalShell';
 import { ResizeHandle } from './components/ResizeHandle';
 import { SnippetLibrary } from './components/SnippetLibrary';
 import { SpecEditor } from './components/SpecEditor';
 import { ThemeToggle } from './components/ThemeToggle';
 import { Toaster } from './components/Toaster';
+import { openModal, setConfirm, toggleDatasets } from './modals/ModalCoordinator';
+import { confirm } from './stores/ConfirmStore';
 import { usePanesStore } from './stores/PanesStore';
 import styles from './App.module.css';
 
@@ -21,6 +25,25 @@ export function App() {
   const libraryWidth = usePanesStore((s) => s.libraryWidth);
   const previewWidth = usePanesStore((s) => s.previewWidth);
 
+  // Route the modal coordinator's discard prompt through the in-app confirm
+  // dialog (docs/architecture/03 → "The coordinator seam").
+  useEffect(() => {
+    setConfirm((message) => confirm({ title: 'Discard changes?', message, danger: true }));
+  }, []);
+
+  // Cmd/Ctrl+K toggles the Datasets manager (spec §05 → Opening). The full
+  // keyboard router (other shortcuts) lands in M6 (docs/architecture/04).
+  useEffect(() => {
+    const onKey = (e: KeyboardEvent) => {
+      if ((e.metaKey || e.ctrlKey) && (e.key === 'k' || e.key === 'K')) {
+        e.preventDefault();
+        toggleDatasets();
+      }
+    };
+    window.addEventListener('keydown', onKey);
+    return () => window.removeEventListener('keydown', onKey);
+  }, []);
+
   return (
     <div className={styles.app}>
       {/* Skip link (WCAG 2.4.1 / GOV.UK): the first focusable element, hidden
@@ -32,6 +55,15 @@ export function App() {
         <h1 className={styles.title}>Astrolabe</h1>
         <span className={styles.version}>v{__APP_VERSION__}</span>
         <span className={styles.spacer} />
+        <button
+          type="button"
+          className={styles.headerButton}
+          onClick={() => openModal('datasets')}
+          aria-keyshortcuts="Meta+K Control+K"
+          title="Datasets (⌘/Ctrl+K)"
+        >
+          Datasets
+        </button>
         <ThemeToggle />
       </header>
 
@@ -60,8 +92,12 @@ export function App() {
         </section>
       </main>
 
-      {/* Global confirmation layer — sits above the (future) feature-modal
-          shell so a discard-changes prompt can appear over an open modal. */}
+      {/* The one feature modal (Datasets / Extract / …), rendered from the
+          registry by the shared shell. At most one open at a time (spec §01C). */}
+      <ModalShell />
+
+      {/* Global confirmation layer — sits above the feature-modal shell so a
+          discard-changes prompt can appear over an open modal. */}
       <ConfirmDialog />
 
       {/* Non-blocking notifications (failed saves, etc.) — top-right toasts,