Split Web App Settings into tabs; allow unset plugin Control mode

Web App: Settings is now two tabs — Personal settings (account,
appearance, profile, privacy, advanced/danger) and Integrations
(Toyota, Anker Solix). Panels use v-show so loaded state and in-flight
edits survive a tab switch. Adds settings.tabs.* labels (en/pl/da).

API Server panel: non-required select config fields now render a
leading "Not set" option, so a superadmin can leave the Anker Solix
Control mode (and Toyota Brand) unset at the global layer. Previously
every option was a real value, forcing a pick that won the cascade and
locked organizations and users out of choosing their own mode. The
server side already treated an empty value as "abstain"; this closes
the UI gap. Adds plugins.notSet label (en/pl/da) and rebuilds the
embedded panel dist.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

API Server/panel/src/components/PluginsCard.vue

@@ -187,6 +187,9 @@ const healthClass = (s) =>
               {{ f.label || f.key }}<span v-if="f.required" class="text-danger"> *</span>
             </label>
             <select v-if="f.type === 'select'" v-model="drafts[p.name][f.key]" class="dh-select">
+              <!-- A non-required select can be left unset (empty), so the global
+                   layer abstains and lower layers (org / user) may choose. -->
+              <option v-if="!f.required" value="">{{ t("plugins.notSet") }}</option>
               <option v-for="o in f.options || []" :key="o.value" :value="o.value">
                 {{ o.label || o.value }}
               </option>