refactor: move shared utilities to lib/shared/ sub-packages

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

frontend/src/lib/ocr/TrainingHistory.svelte

@@ -1,6 +1,6 @@
 <script lang="ts">
 import { m } from '$lib/paraglide/messages.js';
-import type { TrainingRun } from '$lib/types/training.js';
+import type { TrainingRun } from '$lib/ocr/training.js';
 
 interface Props {
 	runs: TrainingRun[];