refactor(frontend): migracion a Mantine y limpieza de widgets

- Migra el frontend a Mantine v9 siguiendo la regla de theming del registry (@fn_library, sin Tailwind/cn/CVA).
- Reescribe DashboardShell, FilterBar, Section, WidgetRenderer y todos los widgets (Area/Bar/Line/Pie/KPI/Sparkline/Table) con componentes y props de Mantine.
- Ajusta vite.config, main.tsx, App.tsx, app.css y env.d.ts.
- Añade postcss.config.cjs requerido por Mantine.
- Actualiza package.json y pnpm-lock.
- Ajusta config.go, main.go y los ejemplos (fn_registry_apps/overview) para el nuevo esquema de tipos en frontend/src/types.ts.

main.go

@@ -122,9 +122,9 @@ func main() {
 	engine := NewQueryEngine(cfg, pool)
 	app := NewApp(cfg, engine, pool, dashDir, *dashboardPath)
 
-	log.Printf("starting wails — title=%q width=%d height=%d dashDir=%q", cfg.Settings.Title, cfg.Settings.Width, cfg.Settings.Height, dashDir)
+	log.Printf("starting wails — title=%q width=%d height=%d layout=%q dashDir=%q", cfg.Settings.Title, cfg.Settings.Width, cfg.Settings.Height, cfg.Settings.Layout, dashDir)
 
-	runErr := wails.Run(&options.App{
+	wailsOpts := &options.App{
 		Title:  cfg.Settings.Title,
 		Width:  cfg.Settings.Width,
 		Height: cfg.Settings.Height,
@@ -136,7 +136,17 @@ func main() {
 		Bind: []interface{}{
 			app,
 		},
-	})
+	}
+
+	if cfg.Settings.Layout == "single_view" {
+		wailsOpts.MaxWidth = cfg.Settings.Width
+		wailsOpts.MaxHeight = cfg.Settings.Height
+		wailsOpts.MinWidth = cfg.Settings.Width
+		wailsOpts.MinHeight = cfg.Settings.Height
+		wailsOpts.DisableResize = true
+	}
+
+	runErr := wails.Run(wailsOpts)
 
 	if runErr != nil {
 		log.Printf("ERROR wails.Run: %v", runErr)