fix: setup wizard logo not loading

The logo handler tried os.ReadFile() on a non-existent filesystem path.
The SVG only exists as an embedded string constant in the web package.
Export FelhomLogoSVG and serve it directly in the setup handler.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

controller/internal/web/server.go

@@ -278,7 +278,7 @@ func (s *Server) serveChartJSHandler(w http.ResponseWriter, r *http.Request) {
 func (s *Server) serveLogoHandler(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "image/svg+xml")
 	w.Header().Set("Cache-Control", "public, max-age=86400")
-	fmt.Fprint(w, felhomLogoSVG)
+	fmt.Fprint(w, FelhomLogoSVG)
 }
 
 // serveAsset serves baked-in app assets (logos, screenshots) from /usr/share/felhom/assets/