feat: add onboarding

src/components/HomeView.tsx

@@ -1,7 +1,7 @@
 import { useStore } from "../store";
 
-export default function HomeView() {
-  const { guides, openGuide, profiles, activeProfileId } = useStore();
+export default function HomeView({ needsSync, onSync }: { needsSync?: boolean; onSync?: () => void }) {
+  const { guides, openGuide, profiles, activeProfileId, syncing } = useStore();
 
   const activeProfile = profiles.find(p => p.id === activeProfileId);
   const totalQuests = guides.reduce((s, g) => s + g.total_quests, 0);
@@ -24,6 +24,39 @@ export default function HomeView() {
         )}
       </div>
 
+      {/* First-time sync CTA */}
+      {needsSync && (
+        <div style={{
+          background: "rgba(240,192,64,0.06)", border: "1px solid rgba(240,192,64,0.35)",
+          borderRadius: "10px", padding: "20px 24px", marginBottom: "24px",
+          display: "flex", flexDirection: "column", alignItems: "center", gap: "12px",
+          textAlign: "center",
+        }}>
+          <div style={{ fontSize: "11px", fontWeight: 600, color: "#f0c040", textTransform: "uppercase", letterSpacing: "0.1em" }}>
+            Première utilisation
+          </div>
+          <p style={{ fontSize: "13px", color: "#94a3b8", lineHeight: 1.6, margin: 0 }}>
+            Aucun guide chargé. Synchronisez pour récupérer les données depuis Google Sheets.
+          </p>
+          <button
+            onClick={onSync}
+            disabled={!onSync || syncing}
+            style={{
+              background: "#f0c040", color: "#0d1117", border: "none",
+              padding: "9px 24px", borderRadius: "8px", fontWeight: 700,
+              fontSize: "13px", cursor: onSync && !syncing ? "pointer" : "default",
+              display: "flex", alignItems: "center", gap: "8px",
+              opacity: onSync && !syncing ? 1 : 0.5,
+            }}
+          >
+            <svg width="14" height="14" viewBox="0 0 24 24" fill="currentColor">
+              <path d="M12 4V1L8 5l4 4V6c3.31 0 6 2.69 6 6 0 1.01-.25 1.97-.7 2.8l1.46 1.46C19.54 15.03 20 13.57 20 12c0-4.42-3.58-8-8-8zm0 14c-3.31 0-6-2.69-6-6 0-1.01.25-1.97.7-2.8L5.24 7.74C4.46 8.97 4 10.43 4 12c0 4.42 3.58 8 8 8v3l4-4-4-4v3z"/>
+            </svg>
+            Synchroniser les guides
+          </button>
+        </div>
+      )}
+
       {/* Global progress */}
       {guides.length > 0 && (
         <div style={{