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/global/+page.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
 import type { PageData } from './$types';
 import TrainingHistory from '$lib/components/TrainingHistory.svelte';
+import * as m from '$lib/paraglide/messages.js';
 
 let { data }: { data: PageData } = $props();
 </script>
@@ -19,10 +20,10 @@ let { data }: { data: PageData } = $props();
 				stroke-width="2"
 				><path stroke-linecap="round" stroke-linejoin="round" d="M15 19l-7-7 7-7" /></svg
 			>
-			OCR
+			{m.admin_tab_ocr()}
 		</a>
 		<h1 class="font-sans text-lg font-bold tracking-widest text-brand-navy uppercase">
-			Global History
+			{m.ocr_global_history_heading()}
 		</h1>
 	</div>