[v0.9] Wire up theme in Angular renderer basic catalog

[jacobsimionato]

Implement plumbing to apply the surface theme (specifically primaryColor) to components in the Angular basic catalog. This involves setting CSS custom properties on the surface host and updating component styles.

This is a child issue of #686.

[jacobsimionato]

Coding agent prompt: Implement plumbing to apply the surface theme (specifically primaryColor) to components in the Angular basic catalog.

Implementation Strategy

1. Surface Integration: Modify @renderers/angular/v0_9/core/surface.component.ts. In the SurfaceComponent, set the --a2ui-primary-color CSS variable on the component's host element or a root wrapper based on surface.theme.primaryColor.
2. Component Updates: Update the @Component styles for implementations in @renderers/angular/v0_9/catalog/basic/. Replace hardcoded colors (like #007bff) with var(--a2ui-primary-color, #007bff).
3. Affected Components:
   • button.component.ts: Primary variant styles.
   • tabs.component.ts: Active tab indicators.
   • choice-picker.component.ts: Selected states.
   • slider.component.ts: Range input highlights.
   • check-box.component.ts: Checked state.

Requirements

• Use standard Angular [style.--a2ui-primary-color] binding or Renderer2 to apply the variable.
• Ensure proper fallback values are maintained in the CSS var() calls.

Context

• @renderers/angular/v0_9/core/surface.component.ts
• @renderers/angular/v0_9/catalog/basic/
• @renderers/web_core/src/v0_9/state/surface-model.ts