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/OcrModelsTable.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
 import type { components } from '$lib/generated/api';
+import * as m from '$lib/paraglide/messages.js';
 type SenderModel = components['schemas']['SenderModel'];
 
 let {
@@ -17,23 +18,23 @@ let {
 			<tr>
 				<th
 					class="border-brand-sand border-b pb-3 text-left text-xs font-bold tracking-widest text-gray-400 uppercase"
-					>Person</th
+					>{m.ocr_table_person()}</th
 				>
 				<th
 					class="border-brand-sand border-b pb-3 text-left text-xs font-bold tracking-widest text-gray-400 uppercase"
-					>CER</th
+					>{m.ocr_table_cer()}</th
 				>
 				<th
 					class="border-brand-sand border-b pb-3 text-left text-xs font-bold tracking-widest text-gray-400 uppercase"
-					>Accuracy</th
+					>{m.ocr_table_accuracy()}</th
 				>
 				<th
 					class="border-brand-sand border-b pb-3 text-left text-xs font-bold tracking-widest text-gray-400 uppercase"
-					>Lines</th
+					>{m.ocr_table_lines()}</th
 				>
 				<th
 					class="border-brand-sand border-b pb-3 text-left text-xs font-bold tracking-widest text-gray-400 uppercase"
-					>Actions</th
+					>{m.ocr_table_actions()}</th
 				>
 			</tr>
 		</thead>
@@ -57,10 +58,16 @@ let {
 					<td class="border-brand-sand/50 border-b py-3">
 						<a
 							href="/admin/ocr/{model.personId}"
-							class="font-medium text-brand-navy hover:underline">Details</a
+							class="font-medium text-brand-navy hover:underline">{m.ocr_table_details()}</a
 						>
 					</td>
 				</tr>
+			{:else}
+				<tr>
+					<td colspan="5" class="py-6 text-center text-sm text-gray-400">
+						{m.ocr_no_models()}
+					</td>
+				</tr>
 			{/each}
 		</tbody>
 	</table>