fix(settings): repair admin panel on Nextcloud 35

[rikled]

Clicking any option in the admin panel (a format checkbox, "Enable live-viewing mode", "Enable watermarking", "Enable plugins"..) blanks the settings page on (at least) NC 35. Fixing that surfaced a second, older bug: watermark settings never persisted.

1. fix(settings): repair admin panel on Nextcloud 35
   The template still uses the deprecated class="checkbox" / class="radio" markup, where core CSS moves the real input off-canvas (inset-inline-start: -10000px) and paints a fake control via label::before. NC 35 no longer renders app settings in place: SettingsContentWrapper.vue replaceChildren()-moves the markup into a Vue-managed container inside NcAppContent, which the off-canvas inputs do not survive. Format checkboxes have no app JS bound at all, confirming the markup is the trigger.

   • render real, in-flow checkboxes/radios scoped to .section-eurooffice
   • stop the generic input { width: 250px } rule applying to checkboxes
   • guard the unprotected sameTab handler, which aborted the rest of init
   • replace the select2 group/tag pickers with NcSettingsSelectGroup / NcSelectTags via a new ListPicker.vue, keeping the hidden inputs as the wire format (fixes Can't set the Grouprights #135, bug: Could not find resource core/js/dist/systemtags.js to load #140)
   • drop the resulting jQuery, underscore, OC.SystemTags and core/dist/systemtags dependencies

2. fix(settings): accept JSON booleans when saving watermark settings
   setWatermarkSettings() compared enabled against the string "true", so every save stored watermark_enabled = "no" and returned early, discarding text, flags and lists. Regressed in 51e2d6a, which switched the admin panel from form-encoded $.ajax to JSON via axios; getFormats() was adapted at the time, the watermark path was not. Added AppConfig::isTrue() and routed all three call sites through it.

Follow-up: the checkbox CSS is still a stopgap: it wins on specificity against legacy core styles slated for removal. Those controls should move to NcCheckboxRadioSwitch / NcSettingsSection next.

Assisted-by: Claude Code:Opus 5

[moodyjmz]

`src/settings.js:596-604` mounts FontManager behind `requestAnimationFrame` + a DOM-persisted `dataset.euroofficeMounted` flag, but the four `ListPicker` mounts (`:74`, `mountedPickers`) use a plain in-memory `Set` that resets on every script execution. What symptom prompted the FontManager guard — a script re-run, or just defensive timing around `SettingsContentWrapper.vue`'s move? If the settings bundle can genuinely execute twice, the `ListPicker` mounts are exposed to the same double-mount risk and the fix is incomplete; if it can't, the rAF + dataset guard is dead weight. Worth clarifying either way.

[rikled]

Thanks, was indeed unnecessary. Please check again :)