Implement Stage 3: Enhance content metadata and validation features

- Added entity metadata fields to the Tasks model, including entity_type, taxonomy, and cluster_role.
- Updated CandidateEngine to prioritize content relevance based on cluster mappings.
- Introduced metadata completeness scoring in ContentAnalyzer.
- Enhanced validation services to check for entity type and mapping completeness.
- Updated frontend components to display and validate new metadata fields.
- Implemented API endpoints for content validation and metadata persistence.
- Migrated existing data to populate new metadata fields for Tasks and Content.

frontend/src/config/pages/content.config.tsx

@@ -204,6 +204,94 @@ export const createContentPageConfig = (
           <SourceBadge source={(row.source as ContentSource) || 'igny8'} />
         ),
       },
+      // Stage 3: Metadata columns
+      {
+        key: 'entity_type',
+        label: 'Entity Type',
+        sortable: true,
+        sortField: 'entity_type',
+        width: '120px',
+        defaultVisible: true,
+        render: (value: string, row: Content) => {
+          const entityType = value || row.entity_type;
+          if (!entityType) {
+            return <span className="text-gray-400 dark:text-gray-500">-</span>;
+          }
+          const typeLabels: Record<string, string> = {
+            'blog_post': 'Blog Post',
+            'article': 'Article',
+            'product': 'Product',
+            'service': 'Service',
+            'taxonomy': 'Taxonomy',
+            'page': 'Page',
+          };
+          return (
+            <Badge color="info" size="sm" variant="light">
+              {typeLabels[entityType] || entityType}
+            </Badge>
+          );
+        },
+      },
+      {
+        key: 'cluster',
+        label: 'Cluster',
+        sortable: false,
+        width: '150px',
+        defaultVisible: true,
+        render: (_value: any, row: Content) => {
+          const clusterName = row.cluster_name;
+          if (!clusterName) {
+            return <span className="text-gray-400 dark:text-gray-500">-</span>;
+          }
+          return (
+            <Badge color="primary" size="sm" variant="light">
+              {clusterName}
+            </Badge>
+          );
+        },
+      },
+      {
+        key: 'cluster_role',
+        label: 'Role',
+        sortable: true,
+        sortField: 'cluster_role',
+        width: '100px',
+        defaultVisible: false,
+        render: (value: string, row: Content) => {
+          const role = value || row.cluster_role;
+          if (!role) {
+            return <span className="text-gray-400 dark:text-gray-500">-</span>;
+          }
+          const roleColors: Record<string, 'primary' | 'success' | 'warning'> = {
+            'hub': 'primary',
+            'supporting': 'success',
+            'attribute': 'warning',
+          };
+          return (
+            <Badge color={roleColors[role] || 'primary'} size="sm" variant="light">
+              {role.charAt(0).toUpperCase() + role.slice(1)}
+            </Badge>
+          );
+        },
+      },
+      {
+        key: 'taxonomy',
+        label: 'Taxonomy',
+        sortable: false,
+        width: '150px',
+        defaultVisible: false,
+        render: (_value: any, row: Content) => {
+          const taxonomyName = row.taxonomy_name;
+          if (!taxonomyName) {
+            return <span className="text-gray-400 dark:text-gray-500">-</span>;
+          }
+          return (
+            <Badge color="purple" size="sm" variant="light">
+              {taxonomyName}
+            </Badge>
+          );
+        },
+      },
       {
         key: 'sync_status',
         label: 'Sync Status',
@@ -349,6 +437,21 @@ export const createContentPageConfig = (
           { value: 'publish', label: 'Publish' },
         ],
       },
+      // Stage 3: Entity type filter
+      {
+        key: 'entity_type',
+        label: 'Entity Type',
+        type: 'select',
+        options: [
+          { value: '', label: 'All Types' },
+          { value: 'blog_post', label: 'Blog Post' },
+          { value: 'article', label: 'Article' },
+          { value: 'product', label: 'Product' },
+          { value: 'service', label: 'Service' },
+          { value: 'taxonomy', label: 'Taxonomy' },
+          { value: 'page', label: 'Page' },
+        ],
+      },
       {
         key: 'source',
         label: 'Source',