feat(KB-022): add GitHub issue status badges to task cards

- Extend core types with GitHub issue tracking fields (issueNumber, issueStatus, lastIssueSync)
- Add TaskStore.getTaskGitHubIssueInfo() to fetch issue details from GitHub API
- Create server-side API endpoint for issue status lookup with caching
- Build GitHubBadge component with color-coded status indicators (open/closed)
- Integrate badges into TaskCard with hover state linking to GitHub issues
- Add CSS styles for badge positioning and visual polish
- Include comprehensive tests for GitHubBadge and TaskCard badge rendering

packages/dashboard/app/styles.css

@@ -1705,6 +1705,44 @@ body {
   color: var(--text-muted);
 }
 
+/* === GitHub Badges === */
+.card-github-badge {
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+  font-size: 11px;
+  padding: 2px 6px;
+  border-radius: 10px;
+  cursor: pointer;
+  transition: filter 0.15s ease, transform 0.1s ease;
+  user-select: none;
+}
+
+.card-github-badge:hover {
+  filter: brightness(1.15);
+}
+
+.card-github-badge:active {
+  transform: scale(0.95);
+}
+
+/* Modifier classes for state-based styling */
+.card-github-badge--open {
+  /* Green styling applied via inline styles */
+}
+
+.card-github-badge--closed {
+  /* Red styling applied via inline styles */
+}
+
+.card-github-badge--merged {
+  /* Purple styling applied via inline styles */
+}
+
+.card-github-badge--completed {
+  /* Purple styling applied via inline styles */
+}
+
 /* Card saving state */
 .card.card-saving {
   opacity: 0.7;