tmf-viewer: host [hidden] nascosto, wizard usa viewer-error al posto della sonda, test_dxf_preview senza zoom del wizard (Refs #122)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019A9CSrh9rfM5WwqKtg8BSE

src/frontend/flask_app/static/js/image_viewer.js

@@ -47,6 +47,8 @@
     'tmf-viewer{display:block;position:relative;overflow:hidden;background:#1f2937;min-width:0}',
     'tmf-viewer *{box-sizing:border-box}',
     'tmf-viewer [hidden]{display:none!important}',
+    // #122: anche l'host con l'attributo hidden si nasconde (display:block sopra vincerebbe sul [hidden] del browser)
+    'tmf-viewer[hidden]{display:none!important}',
     'tmf-viewer .tmfv-vp{position:absolute;top:0;right:0;bottom:0;left:0;overflow:auto;display:flex}',
     'tmf-viewer[fit-height] .tmfv-vp{position:relative;width:100%}',
     'tmf-viewer .tmfv-stage{position:relative;flex:none;margin:auto;user-select:none;-webkit-user-select:none}',