feat(frontend): implement main dashboard page (#48)

Implement the main dashboard / projects list page for Syndarix as the landing
page after login. The implementation includes:

Dashboard Components:
- QuickStats: Overview cards showing active projects, agents, issues, approvals
- ProjectsSection: Grid/list view with filtering and sorting controls
- ProjectCardGrid: Rich project cards for grid view
- ProjectRowList: Compact rows for list view
- ActivityFeed: Real-time activity sidebar with connection status
- PerformanceCard: Performance metrics display
- EmptyState: Call-to-action for new users
- ProjectStatusBadge: Status indicator with icons
- ComplexityIndicator: Visual complexity dots
- ProgressBar: Accessible progress bar component

Features:
- Projects grid/list view with view mode toggle
- Filter by status (all, active, paused, completed, archived)
- Sort by recent, name, progress, or issues
- Quick stats overview with counts
- Real-time activity feed sidebar with live/reconnecting status
- Performance metrics card
- Create project button linking to wizard
- Responsive layout for mobile/desktop
- Loading skeleton states
- Empty state for new users

API Integration:
- useProjects hook for fetching projects (mock data until backend ready)
- useDashboardStats hook for statistics
- TanStack Query for caching and data fetching

Testing:
- 37 unit tests covering all dashboard components
- E2E test suite for dashboard functionality
- Accessibility tests (keyboard nav, aria attributes, heading hierarchy)

Technical:
- TypeScript strict mode compliance
- ESLint passing
- WCAG AA accessibility compliance
- Mobile-first responsive design
- Dark mode support via semantic tokens
- Follows design system guidelines

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/features/issues/components/ActivityTimeline.tsx

@@ -0,0 +1,84 @@
+'use client';
+
+/**
+ * ActivityTimeline Component
+ *
+ * Displays issue activity history.
+ *
+ * @module features/issues/components/ActivityTimeline
+ */
+
+import { MessageSquare, Bot, User } from 'lucide-react';
+import { Button } from '@/components/ui/button';
+import { Card, CardHeader, CardTitle, CardContent } from '@/components/ui/card';
+import { cn } from '@/lib/utils';
+import type { IssueActivity } from '../types';
+
+interface ActivityTimelineProps {
+  activities: IssueActivity[];
+  onAddComment?: () => void;
+  className?: string;
+}
+
+export function ActivityTimeline({
+  activities,
+  onAddComment,
+  className,
+}: ActivityTimelineProps) {
+  return (
+    <Card className={className}>
+      <CardHeader>
+        <div className="flex items-center justify-between">
+          <CardTitle className="flex items-center gap-2">
+            <MessageSquare className="h-5 w-5" aria-hidden="true" />
+            Activity
+          </CardTitle>
+          {onAddComment && (
+            <Button variant="outline" size="sm" onClick={onAddComment}>
+              Add Comment
+            </Button>
+          )}
+        </div>
+      </CardHeader>
+      <CardContent>
+        <div className="space-y-6" role="list" aria-label="Issue activity">
+          {activities.map((item, index) => (
+            <div
+              key={item.id}
+              className="flex gap-4"
+              role="listitem"
+            >
+              <div className="relative flex flex-col items-center">
+                <div className="flex h-8 w-8 items-center justify-center rounded-full bg-muted">
+                  {item.actor.type === 'agent' ? (
+                    <Bot className="h-4 w-4" aria-hidden="true" />
+                  ) : (
+                    <User className="h-4 w-4" aria-hidden="true" />
+                  )}
+                </div>
+                {index < activities.length - 1 && (
+                  <div className="absolute top-8 h-full w-px bg-border" aria-hidden="true" />
+                )}
+              </div>
+              <div className={cn('flex-1', index < activities.length - 1 && 'pb-6')}>
+                <div className="flex flex-wrap items-baseline gap-2">
+                  <span className="font-medium">{item.actor.name}</span>
+                  <span className="text-sm text-muted-foreground">{item.message}</span>
+                </div>
+                <p className="text-xs text-muted-foreground">
+                  <time dateTime={item.timestamp}>{item.timestamp}</time>
+                </p>
+              </div>
+            </div>
+          ))}
+        </div>
+
+        {activities.length === 0 && (
+          <div className="py-8 text-center text-muted-foreground">
+            No activity yet
+          </div>
+        )}
+      </CardContent>
+    </Card>
+  );
+}