Adds a shared bulma_variants.py (color/size option lists) and expands BULMA_*_CONTROLS in bulma_controls.py to cover each component's full modifier set: Bouton (colour incl. white/light/dark/black/text, light-shade toggle, size, rounded, outlined, inverted, static, loading, fullwidth), Titre (Bulma size is-1..is-6 independent of heading level, is-spaced), Jauge (size), Tableau (bordered/fullwidth/striped/hoverable/narrow, now toggleable instead of hardcoded), Onglets (alignment, boxed/toggle/toggle-rounded style, size, fullwidth), and every form field — champ_texte/email/mot_de_passe, zone_texte, liste_deroulante (colour, size, rounded, static).
render_select.py/render_onglets.py/render_jauge.py now redirect the merged "class" from _visible_attrs to the actual Bulma sub-element (the .select wrapper, the .tabs div, the <progress> tag) instead of the outer positioning wrapper, since that's what needs to carry the modifier classes.
Also fixed a real latent bug found while wiring this up: a checkbox control with default=True (e.g. Tableau's "Première ligne = en-tête") was never actually applied on a freshly created element — default_style_and_attributes unconditionally skipped ALL checkbox types at creation, so the panel showed it checked while the element itself had nothing set. Now a checkbox's default=True is frozen at creation like any other meaningful default; default=False (the common case) is unaffected.
Verified end to end: every widget's variant controls save and render the right class tokens (spot-checked titre/tableau/onglets/champ_texte/liste_deroulante/jauge), full suite green (89 passed).
Adds a new "class:" control-target kind (save_element_controls.py, _visible_attrs.py) alongside the existing content/attr/style ones, so a widget can carry CSS classes built from independent named slots (color, size, shape...) without them overwriting each other. Bouton and Titre get their Bulma base class (button/title) via fixed_attrs; Conteneur gets an opt-in "Carte (Bulma)" preset instead of a forced default, since it's also used as an invisible layout wrapper. Bouton's font-size/border-radius sliders no longer freeze their default value into inline style at creation (new c_slider no_freeze flag), so Bulma's own button styling shows through until a user actually customizes it — inline style still wins over any class the moment it's set, exactly like today.
Loads bulma.min.css via CDN in screen_edit.html and play.html, same pattern as animate.css.
william