Make Jauge, Onglets, and every form-field widget real native Bulma elements

- Jauge now renders a real <progress class="progress"> instead of a hand-built pair of absolutely-positioned divs. The bas/haut color interpolation still works, set via Bulma's own --bulma-progress-value-background-color CSS custom property rather than fighting the class.
- Onglets' tab strip is now genuine Bulma tabs markup (tabs > ul > li, is-active on the li) instead of custom forgeTabBar/forgeTabBtn classes; forgeShowTab (duplicated in screen_edit.html and play.html) now toggles is-active to match.
- Champ texte/email/mot de passe get class="input", Zone de texte gets class="textarea", Case à cocher/Bouton radio's existing <label> wrapper gets class="checkbox"/"radio" (Bulma's own convention — the structure already matched, just needed the class), Liste déroulante is wrapped in Bulma's required <div class="select"> (a bare class on the <select> itself has zero effect in Bulma), Tableau gets class="table is-bordered is-fullwidth" with the per-cell inline borders removed so Bulma's own table styling applies.
- Removed the now-dead .forgeTabBar/.forgeTabBtn CSS.

Updated tests/test_jauge.py and tests/test_onglets_widget.py assertions to match the new markup (value="X" attribute instead of width:X% inline style, --bulma-progress-value-background-color instead of background-color, forgeShowTab(this) marker instead of the removed forgeTabBtn class) — same behavior, different rendering mechanism. Full suite green (89 passed), verified end to end against the real "test" project via the actual /play route.

screens/widgets/registry.py

@@ -100,7 +100,7 @@ WIDGETS = {
     },
     "champ_texte": {
         "label": "Champ — texte", "icon": "⌨️", "tag": "input", "has_content": False, "self_closing": True,
-        "w": 40, "h": 8, "default_content": "", "fixed_attrs": {"type": "text"},
+        "w": 40, "h": 8, "default_content": "", "fixed_attrs": {"type": "text", "class": "input"},
         "controls": [
             c_text("placeholder", "Texte indicatif", "attr:placeholder", placeholder="ex. Votre réponse", group="Contenu"),
             c_text("name", "Nom du champ", "attr:name", placeholder="ex. reponse1", group="Contenu"),
@@ -109,7 +109,7 @@ WIDGETS = {
     },
     "champ_email": {
         "label": "Champ — email", "icon": "📧", "tag": "input", "has_content": False, "self_closing": True,
-        "w": 40, "h": 8, "default_content": "", "fixed_attrs": {"type": "email"},
+        "w": 40, "h": 8, "default_content": "", "fixed_attrs": {"type": "email", "class": "input"},
         "controls": [
             c_text("placeholder", "Texte indicatif", "attr:placeholder", placeholder="ex. votre@email.com", default="votre@email.com", group="Contenu"),
             c_text("name", "Nom du champ", "attr:name", placeholder="ex. email", group="Contenu"),
@@ -118,7 +118,7 @@ WIDGETS = {
     },
     "champ_mot_de_passe": {
         "label": "Champ — mot de passe", "icon": "🔒", "tag": "input", "has_content": False, "self_closing": True,
-        "w": 40, "h": 8, "default_content": "", "fixed_attrs": {"type": "password"},
+        "w": 40, "h": 8, "default_content": "", "fixed_attrs": {"type": "password", "class": "input"},
         "controls": [
             c_text("placeholder", "Texte indicatif", "attr:placeholder", placeholder="ex. Mot de passe", group="Contenu"),
             c_text("name", "Nom du champ", "attr:name", placeholder="ex. mot_de_passe", group="Contenu"),
@@ -149,7 +149,7 @@ WIDGETS = {
     },
     "zone_texte": {
         "label": "Zone de texte", "icon": "🗒️", "tag": "textarea", "has_content": False,
-        "w": 40, "h": 18, "default_content": "",
+        "w": 40, "h": 18, "default_content": "", "fixed_attrs": {"class": "textarea"},
         "controls": [
             c_text("placeholder", "Texte indicatif", "attr:placeholder", placeholder="ex. Votre message", group="Contenu"),
             c_text("name", "Nom du champ", "attr:name", placeholder="ex. message", group="Contenu"),
@@ -195,6 +195,7 @@ WIDGETS = {
     "tableau": {
         "label": "Tableau", "icon": "🗂️", "tag": "table", "has_content": True, "special_render": "table",
         "w": 55, "h": 25, "default_content": "Colonne 1;Colonne 2\nValeur A;Valeur B",
+        "fixed_attrs": {"class": "table is-bordered is-fullwidth"},
         "controls": [
             c_textarea("content", "Contenu — une ligne par rangée, colonnes séparées par ;", "content",
                        default="Colonne 1;Colonne 2\nValeur A;Valeur B", group="Contenu"),