fix(import): address non-blocking review feedback — touch target, glossary, edge-case test

- Add min-h-[44px] py-2 to <summary> in ImportStatusCard for 44 px touch target
- Add SkippedFile and skipped count entries to docs/GLOSSARY.md
- Add MassImportServiceTest case: ALREADY_EXISTS fires before file I/O when doc is UPLOADED and file is present on disk

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

frontend/src/routes/admin/system/ImportStatusCard.svelte

@@ -59,7 +59,7 @@ function reasonLabel(code: string): string {
 		<div aria-live="polite">
 			{#if importStatus.skipped > 0}
 				<details class="mb-4 rounded-sm border border-warning/40 bg-warning/10 p-4 text-amber-900">
-					<summary class="flex cursor-pointer list-none items-center gap-2">
+					<summary class="flex min-h-[44px] cursor-pointer list-none items-center gap-2 py-2">
 						<svg
 							aria-hidden="true"
 							class="details-chevron h-4 w-4 shrink-0 motion-safe:transition-transform"