fix(dashboard): UI polish — modals, layout, consistency, test fixes

Dashboard UX polish pass — consolidates create forms into modals
triggered from the page header, fixes layout inconsistencies, adds
scroll-to navigation for the Keys page, and aligns the TokenBar with
the design system.

Changes:
- App.tsx: add padding to sidebar header
- resolve-page-title.ts: add missing routes, better fallback title
- en.ts: fix nav labels (Profiles was 'profiles : multi agents')
- ModelsPage: two-col layout, auxiliary tasks modal, TokenBar redesign
- ProfilesPage: create button in header, form in modal, Checkbox component
- CronPage: create button in header, form in modal
- EnvPage: scroll-to sub-nav in header, fix text overflow

Modal and dialog standardization:
- Replace all native confirm()/window.confirm() with ConfirmDialog
  (OAuthProvidersCard, PluginsPage, ModelsPage, ConfigPage)
- Add useModalBehavior hook (Escape-to-close, scroll lock, focus restore)
- Apply hook to ProfilesPage, CronPage, AuxiliaryTasksModal

Component fixes (from PR review):
- Checkbox: fix controlled/uncontrolled mismatch, add focus-visible ring
- TokenBar: add rounded-full to legend dots, remove dead code

CI/test fixes:
- Fix TS unused imports (noUnusedLocals), type-narrow PickerTarget union
- Add windows-footgun suppression on platform-guarded os.killpg
- Fix 19 stale unit tests + 9 e2e tests broken by recent main changes
- Restore minimal example-dashboard plugin for plugin auth test

web/src/components/ui/checkbox.tsx

@@ -0,0 +1,61 @@
+import { cn } from "@/lib/utils";
+import { Check } from "lucide-react";
+
+interface CheckboxProps
+  extends Omit<React.InputHTMLAttributes<HTMLInputElement>, "type"> {
+  label?: React.ReactNode;
+}
+
+export function Checkbox({
+  className,
+  label,
+  id,
+  checked,
+  defaultChecked,
+  ...props
+}: CheckboxProps) {
+  // Support both controlled (checked prop) and uncontrolled (defaultChecked) usage.
+  // For visual rendering, prefer `checked` if provided; otherwise fall back to defaultChecked.
+  const isChecked = checked ?? defaultChecked ?? false;
+
+  return (
+    <label
+      htmlFor={id}
+      className={cn(
+        "group flex items-center gap-2.5 cursor-pointer select-none",
+        props.disabled && "cursor-not-allowed opacity-50",
+      )}
+    >
+      <span
+        className={cn(
+          "flex h-4 w-4 shrink-0 items-center justify-center transition-all",
+          "border bg-background/40",
+          // Focus-visible ring for keyboard accessibility
+          "group-has-[:focus-visible]:ring-2 group-has-[:focus-visible]:ring-ring group-has-[:focus-visible]:ring-offset-1",
+          isChecked
+            ? "border-foreground bg-foreground/20"
+            : "border-border group-hover:border-foreground/40",
+          className,
+        )}
+      >
+        <Check
+          className={cn(
+            "h-3 w-3 transition-opacity",
+            isChecked
+              ? "text-foreground opacity-100"
+              : "text-foreground opacity-0",
+          )}
+        />
+      </span>
+      <input
+        type="checkbox"
+        id={id}
+        checked={checked}
+        defaultChecked={checked === undefined ? defaultChecked : undefined}
+        className="sr-only"
+        {...props}
+      />
+      {label && <span className="text-sm">{label}</span>}
+    </label>
+  );
+}