UI-правки по результатам визуального ревью

Add Vue demo mounts for buttons, inputs, tables and capture inputs section ...

- Add GnButton, GnInput and GnTable Vue demo mounts.

- Switch tables partial to demo-section for screenshot capture.

- Add dismissible alert styles and close button.

- Include Inputs section in screenshot review list.

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

Add Input, Badge, Alert components and foundation demos ...

- Add src/scss/components/_forms.scss with input, label, help text,
  and error/success/warning states.
- Add src/scss/components/_badges.scss and _alerts.scss with semantic
  variants and outline/size options.
- Add GnInput, GnBadge, GnAlert Vue adapters mirroring gnexus-ui-kit API.
- Update plugin and entry exports for new components.
- Add demo partials for Typography, Palette, Utilities, Inputs, Badges,
  and Alerts, and include them in demo/index.html.
- Extend Vue example app to render new components.