ui(onboarding): flat tab navigation + fix vertical-stacked button text

Onboarding was a 7-step linear wizard, same information hierarchy as
Settings but behaving like a modal. Replace with the SettingsShell tab
pattern: one row of six tabs (nodecheck / providers / company /
modelpool / executionmode / mission), free navigation, per-tab
completion ticks derived from the wizard's own validation rules.

Sub-fixes on the same pass:
- ActionButton: add whitespace-nowrap + shrink-0 so "选择" never
  stacks vertically on narrow containers. Global — every caller gets
  the correct behavior
- CompanyStep: CEO Runtime Provider/Model go vertical (space-y-3
  instead of grid-cols-2) so long names like "Fireworks AI" /
  "Kimi K2.5 Turbo Preview 0911" stay readable; workspace-path Input
  wrapped in min-w-0 flex-1 container so it yields, not the button
- MarkdownBody: render react-markdown in chat bubbles (was plain text)

i18n: added onboarding.stepsAria for the tablist label.

src/renderer/components/company-onboarding/ModelPoolStep.tsx

@@ -16,6 +16,7 @@ export function ModelPoolStep({ onBack, onContinue }: ModelPoolStepProps) {
   const {
     connectorModelPools,
     onToggleConnectorModel,
+    onSetAllConnectorModels,
     selectedConnectorId,
     selectedConnectorEnabledModels,
     totalEnabledModels,
@@ -44,31 +45,54 @@ export function ModelPoolStep({ onBack, onContinue }: ModelPoolStepProps) {
       <div className="space-y-3">
         {connectorModelPools.map(({ connector, models }) => {
           const enabledCount = models.filter((model) => model.enabled).length;
+          const allEnabled = models.length > 0 && enabledCount === models.length;
+          // One action, state-aware: when everything is on the next useful
+          // move is "disable all"; otherwise the user almost always wants
+          // "enable all". Two buttons would compete for the user's decision
+          // for no real benefit.
+          const bulkAction = allEnabled
+            ? { label: t("models.disableAll"), target: false }
+            : { label: t("models.enableAll"), target: true };
           return (
             <div key={connector.id} className="rounded-lg border border-border bg-background/50 p-4">
-              <div className="mb-3 flex items-start justify-between gap-3">
-                <div className="min-w-0">
-                  <div className="flex items-center gap-2">
-                    <span className="truncate text-[13px] font-semibold text-foreground">
-                      {connector.id.startsWith("claude_compat") && connector.notes ? connector.notes : connector.label}
+              {/* Row 1 — identity + health. Title has room to breathe. */}
+              <div className="flex items-center justify-between gap-3">
+                <div className="flex min-w-0 items-center gap-2">
+                  <span className="truncate text-[13px] font-semibold text-foreground">
+                    {connector.id.startsWith("claude_compat") && connector.notes ? connector.notes : connector.label}
+                  </span>
+                  {connector.id === selectedConnectorId ? (
+                    <span className="shrink-0 whitespace-nowrap rounded-full bg-accent px-2 py-0.5 text-[10px] font-semibold uppercase tracking-[0.06em] text-primary">
+                      {t("models.ceoRuntime")}
                     </span>
-                    {connector.id === selectedConnectorId ? (
-                      <span className="rounded-full bg-accent px-2 py-0.5 text-[10px] font-semibold uppercase tracking-[0.06em] text-primary">
-                        {t("models.ceoRuntime")}
-                      </span>
-                    ) : null}
-                  </div>
-                  <div className="mt-1 text-[11px] text-muted-foreground">
-                    {t("models.poolSummary").replace("{enabled}", String(enabledCount)).replace("{total}", String(models.length || 0))}
-                  </div>
+                  ) : null}
                 </div>
                 <StatusBadge status={connector.status} />
               </div>
-              <ModelToggleList
-                models={models}
-                onToggle={(modelId) => void onToggleConnectorModel(connector.id, modelId)}
-                canRemove={false}
-              />
+              {/* Row 2 — stats + bulk action. Only rendered when there is */}
+              {/* more than one model (single-model providers have nothing */}
+              {/* meaningful to bulk-toggle). */}
+              <div className="mt-2 flex items-center justify-between gap-3 text-[11px] text-muted-foreground">
+                <span>
+                  {t("models.poolSummary").replace("{enabled}", String(enabledCount)).replace("{total}", String(models.length || 0))}
+                </span>
+                {models.length > 1 ? (
+                  <button
+                    type="button"
+                    onClick={() => onSetAllConnectorModels(connector.id, bulkAction.target)}
+                    className="whitespace-nowrap rounded-md border border-border bg-background/60 px-2 py-1 text-[11px] text-muted-foreground transition hover:border-foreground/40 hover:text-foreground"
+                  >
+                    {bulkAction.label}
+                  </button>
+                ) : null}
+              </div>
+              <div className="mt-3">
+                <ModelToggleList
+                  models={models}
+                  onToggle={(modelId) => void onToggleConnectorModel(connector.id, modelId)}
+                  canRemove={false}
+                />
+              </div>
             </div>
           );
         })}