signature: add systems map, command palette and motion primitives

Ship the Signature UX as standalone, SSR-safe pieces: bilingual copy, a dual SVG/list systems map, a Map-backed command palette in the shell, opt-in reveal and metric primitives, and a leak-free decorative canvas.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/app/app.scss

@@ -29,6 +29,10 @@
   border-radius: var(--radius-lg);
 }
 
+.site-actions app-command-palette {
+  flex: 0 0 auto;
+}
+
 .site-identity,
 .site-nav a,
 .site-actions a,