fix(bulk-upload): form layout polish and drop zone sizing

- Drop zone box doubled: max-w-xl, larger icon (80px), bigger padding and text
- Title field wrapped in its own card (matches WhoWhenSection/DescriptionSection)
- Removed double-wrapping outer card around WhoWhenSection + DescriptionSection
- Added space-y-4 between form sections for consistent breathing room
- ScopeCard per-file label: text-accent → text-primary for legible contrast in light theme

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

frontend/src/lib/components/document/ScopeCard.svelte

@@ -32,7 +32,7 @@ let {
 			</span>
 		</div>
 	{:else}
-		<p class="mb-3 text-xs font-bold tracking-widest text-accent uppercase">
+		<p class="mb-3 text-xs font-bold tracking-widest text-primary uppercase">
 			{m.bulk_scope_per_file_label()}
 		</p>
 	{/if}