- Standardize accent color to cisco-blue (#049fd9) for all interactive
  elements (buttons, checkboxes, radios, focus rings, links)
- Unify card styling: white bg, gray-200 borders, rounded-lg, shadow-sm
- Standardize button styling: rounded-md, consistent padding, font-medium,
  transition-colors, cisco-blue primary / outline secondary
- Standardize input/select styling: rounded-md, cisco-blue focus rings
- Fix text color inconsistencies: replace text-black with text-gray-900,
  use text-gray-500/600 hierarchy for secondary text
- Normalize heading sizes: text-sm font-semibold for card titles,
  text-xl font-semibold for page titles
- Remove inline body background from app.html, use CSS variable instead
- Add --color-surface CSS variable for background consistency
- Unify empty/loading/error state text styling across all components
- Polish error page with outline secondary button and cisco-blue primary
- Clean up singularities table styling with consistent header/cell colors
- Update chart info text to use neutral gray instead of green/checkmark
- Standardize file detail page spacing and router summary card text

Co-authored-by: oliver <flamboh@users.noreply.github.com>