Command palette (cmd+K): page nav, quick actions, ask-the-assistant

Header search trigger + global hotkey. Typing a question surfaces a
'Preguntar' item that lands in Asistente via the same auto-send flow
as the Inicio ask box. Also installs hover-card and calendar for the
remaining Phase 3 work.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/package.json

@@ -24,10 +24,13 @@
     "@tanstack/react-table": "^8.21.3",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
+    "cmdk": "^1.1.1",
     "concurrently": "^9.1.2",
+    "date-fns": "^4.4.0",
     "hono": "^4.12.15",
     "lucide-react": "^1.12.0",
     "react": "19.2.5",
+    "react-day-picker": "^10.0.1",
     "react-dom": "19.2.5",
     "react-router-dom": "^7.6.0",
     "recharts": "^3.8.0",