feat: implement code quality dashboard with architecture violation tracking

Implement comprehensive code quality dashboard (Phase 2-4) to track and manage
architecture violations found by the validation script.

Backend Implementation:
- Add JSON output support to validate_architecture.py script
- Create CodeQualityService with scan management, violation tracking, and statistics
- Implement REST API endpoints for code quality management:
  * POST /admin/code-quality/scan - trigger new architecture scan
  * GET /admin/code-quality/scans - list scan history
  * GET /admin/code-quality/violations - list violations with filtering/pagination
  * GET /admin/code-quality/violations/{id} - get violation details
  * POST /admin/code-quality/violations/{id}/assign - assign to developer
  * POST /admin/code-quality/violations/{id}/resolve - mark as resolved
  * POST /admin/code-quality/violations/{id}/ignore - mark as ignored
  * POST /admin/code-quality/violations/{id}/comments - add comments
  * GET /admin/code-quality/stats - dashboard statistics
- Fix architecture_scan model imports to use app.core.database

Frontend Implementation:
- Create code quality dashboard page (code-quality-dashboard.html)
  * Summary cards for total violations, errors, warnings, health score
  * Status breakdown (open, assigned, resolved, ignored)
  * Trend visualization for last 7 scans
  * Top violating files list
  * Violations by rule and module
  * Quick action links
- Create violations list page (code-quality-violations.html)
  * Filterable table by severity, status, rule ID, file path
  * Pagination support
  * Violation detail view links
- Add Alpine.js components (code-quality-dashboard.js, code-quality-violations.js)
  * Dashboard state management and scan triggering
  * Violations list with filtering and pagination
  * API integration with authentication
- Add "Code Quality" navigation link in admin sidebar (Developer Tools section)

Routes:
- GET /admin/code-quality - dashboard page
- GET /admin/code-quality/violations - violations list
- GET /admin/code-quality/violations/{id} - violation details

Features:
- Real-time scan execution from UI
- Technical debt score calculation (0-100 scale)
- Violation workflow: open → assigned → resolved/ignored
- Trend tracking across multiple scans
- File and module-level insights
- Assignment system with priorities and due dates
- Collaborative comments on violations

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

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

app/templates/admin/partials/sidebar.html

@@ -125,6 +125,17 @@
                     <span class="ml-4">Testing Hub</span>
                 </a>
             </li>
+
+            <!-- Code Quality -->
+            <li class="relative px-6 py-3">
+                <span x-show="currentPage === 'code-quality'" class="absolute inset-y-0 left-0 w-1 bg-purple-600 rounded-tr-lg rounded-br-lg" aria-hidden="true"></span>
+                <a class="inline-flex items-center w-full text-sm font-semibold transition-colors duration-150 hover:text-gray-800 dark:hover:text-gray-200"
+                   :class="currentPage === 'code-quality' ? 'text-gray-800 dark:text-gray-100' : ''"
+                   href="/admin/code-quality">
+                    <span x-html="$icon('shield-check')"></span>
+                    <span class="ml-4">Code Quality</span>
+                </a>
+            </li>
         </ul>
 
         <!-- Settings Section -->
@@ -290,6 +301,17 @@
                     <span class="ml-4">Testing Hub</span>
                 </a>
             </li>
+
+            <!-- Code Quality -->
+            <li class="relative px-6 py-3">
+                <span x-show="currentPage === 'code-quality'" class="absolute inset-y-0 left-0 w-1 bg-purple-600 rounded-tr-lg rounded-br-lg" aria-hidden="true"></span>
+                <a class="inline-flex items-center w-full text-sm font-semibold transition-colors duration-150 hover:text-gray-800 dark:hover:text-gray-200"
+                   :class="currentPage === 'code-quality' ? 'text-gray-800 dark:text-gray-100' : ''"
+                   href="/admin/code-quality">
+                    <span x-html="$icon('shield-check')"></span>
+                    <span class="ml-4">Code Quality</span>
+                </a>
+            </li>
         </ul>
 
         <!-- Settings Section -->