[FEATURE] Add fade-in animation for issue cards

[ascender1729]

Description

Add smooth fade-in animation when issue cards appear in the results list.

Why Needed

• Improves perceived performance
• Polished, professional feel
• Guides user attention to new content

Implementation Details

• Use CSS animation or Svelte transitions
• Stagger animation for sequential cards
• Keep animation subtle and fast (200-300ms)
• Respect prefers-reduced-motion

Files to Modify

• src/components/results/IssueCard.svelte
• src/components/results/ResultsContainer.svelte

Code Example

<script>
  import { fade, fly } from 'svelte/transition';
</script>

{#each issues as issue, i}
  <div 
    in:fly={{ y: 20, delay: i * 50, duration: 300 }}
    class="issue-card"
  >
    <IssueCard {issue} />
  </div>
{/each}

Acceptance Criteria

• Cards animate in smoothly
• Staggered timing for multiple cards
• Respects prefers-reduced-motion
• No layout shift during animation

Time Estimates

• With AI: 135 minutes
• Without AI: 900 minutes