feat(election): candidate photos/symbols, voting interface, withdrawal, live vote counts

- Candidate board: show client profile photos and election symbols via CBS ContentStore
  (lazy-fetch base64 via GET /election/{id}/candidate/{id}/symbol), zoom/drag viewer
- Candidate board: live vote count badge per candidate (VOTING_OPEN/CLOSED only)
- Election dashboard: total voters/votes chips on VOTING_OPEN election cards
- Voting interface: fix candidates not loading (paged response .content extraction),
  lazy-load candidate photos and symbols, gold-bordered symbol on ballot card
- Nomination withdrawal: implement withdraw button in nomination-detail and nomination-list
- ImagePreviewDialogComponent: DomSanitizer support for data: URLs
- election.service: uploadCandidateSymbol (FormData), getCandidateSymbol, getClientImage,
  getVoteSummary methods
- main.scss: ipd-dialog / ipd-backdrop styles for image preview dialog

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

src/main.scss

@@ -46,6 +46,17 @@
   color: #fecaca !important;
 }
 
+// ===== Image Preview Dialog (election candidate photo/symbol viewer) =====
+.ipd-dialog .mat-mdc-dialog-container {
+  padding: 0;
+  border-radius: 10px;
+  overflow: hidden;
+}
+
+.ipd-backdrop {
+  background: rgb(0 0 0 / 75%);
+}
+
 // ===== Sub-menu Mega Panels (rendered in CDK overlay) =====
 .deposits-mega-panel,
 .hrm-mega-panel {