fix(admin): i18n all hardcoded OCR strings, fix personName lookup, add empty state

- Replace hardcoded EN strings in OcrHealthBar/OcrStatCards/OcrModelsTable with
  Paraglide message keys (de/en/es translations added)
- Add role=img + aria-label to OcrHealthBar status dot
- Add {:else} empty-state row in OcrModelsTable
- Fix personName derivation in [personId]/+page.svelte to use params.personId key
  instead of Object.values()[0] (fragile when multiple persons present)
- Update OcrModelsTable spec to assert empty-state row structure (locale-agnostic)
- Add missing availableSegBlocks test to OcrStatCards spec

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

frontend/src/routes/admin/ocr/OcrHealthBar.svelte

@@ -1,14 +1,17 @@
 <script lang="ts">
+import * as m from '$lib/paraglide/messages.js';
 let { ocrServiceAvailable }: { ocrServiceAvailable: boolean } = $props();
 </script>
 
 <div class="flex items-center gap-2">
 	<span
+		role="img"
+		aria-label={ocrServiceAvailable ? m.ocr_status_online() : m.ocr_status_offline()}
 		class="inline-block h-2.5 w-2.5 rounded-full {ocrServiceAvailable
 			? 'bg-green-500'
 			: 'bg-red-500'}"
 	></span>
 	<span class="text-sm font-medium {ocrServiceAvailable ? 'text-green-700' : 'text-red-700'}">
-		{ocrServiceAvailable ? 'Online' : 'Offline'}
+		{ocrServiceAvailable ? m.ocr_status_online() : m.ocr_status_offline()}
 	</span>
 </div>