feat: structured artifact rendering, UX improvements

- Render structured artifacts from agent results with type-aware
  formatting: code blocks with syntax highlighting and copy button,
  terminal-style command output, search result cards, and text findings
- Make FinalResult panel collapsible (default collapsed) with scrollable
  content (max-h-96) to prevent dominating the chat view
- Add clickable URL detection in summaries and artifact content
- Fix code block contrast for both light and dark mode
- Animate progress bar with pulse ring on active step and gradient
  shimmer on connecting lines
- Fix tab-switching bug: use module-level orchestrationStore singleton
  so orchestration state survives route navigation
- Remove sample/demo data seeding and clean up persisted localStorage
  entries from previous sample sessions
- Remove showSampleBadge prop from PageHeader
- Regenerate proto types for new Artifact message and ArtifactType enum
- Update README project structure (remove deleted data/ directory)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/routes/memory/+page.svelte

@@ -39,7 +39,7 @@
 </script>
 
 <div class="flex h-screen flex-col overflow-hidden bg-gray-50 dark:bg-gray-900">
-	<PageHeader title="Memory Candidates" backHref={chatHref} showSampleBadge />
+	<PageHeader title="Memory Candidates" backHref={chatHref} />
 
 	<!-- Filters -->
 	<div class="border-b border-gray-200 dark:border-gray-700 bg-white dark:bg-gray-900 px-4 py-3 md:px-6">