Adds a persistent dark/light theme toggle (localStorage +
data-bs-theme on <html>) so it applies globally, including the
circuit editor route which has no visible sidebar. An inline
beforeInteractive script sets the theme before hydration to avoid a
flash of the wrong theme.
Bootstrap components pick up data-bs-theme automatically; the custom
circuit-grid CSS previously used ~150 hardcoded hex colors, all
converted to semantic tokens in globals.css with light/dark values.
Verified with a headless-browser pass across the project list, project
detail page, circuit editor, project-device drawer and a settings
modal in both themes; no console errors.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
