feat(election): candidate analysis enhancements + overall shareholder analysis page

- candidate-analysis: add family voter influence donut chart (% of total shareholders)
- candidate-analysis: sub-caste breakdown by client lastname
- candidate-analysis: religion profile with candidate match (★) highlighting
- candidate-analysis: remove active savings holders metric, expand grid to 3 cols
- shareholder-analysis: new standalone page showing demographic analysis of all active shareholders (11 charts across gender, age, religion, caste, sub-caste, occupation, education, marital, share-holding, tenure, area)
- candidate-board: add 'Overall Analysis' button navigating to shareholder analysis page
- election-routing: lazy-load route for :electionId/shareholders/analysis
- election.service: add getOverallShareholderAnalysis() API call

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

src/app/election/components/candidate-board/candidate-board.component.scss

@@ -52,6 +52,21 @@
     mat-icon {
       font-size: 18px;
     }
+
+    &.btn-analysis {
+      margin-left: auto;
+      background: linear-gradient(135deg, #4f46e5 0%, #7c3aed 100%);
+      color: #fff;
+      border-color: transparent;
+
+      &:hover {
+        opacity: 0.9;
+      }
+    }
+
+    & + .btn-outline {
+      margin-left: 8px;
+    }
   }
 }