fix(cibg): datablock row separators + filled Bestand-upload button

- Datablock entries had no separators: CIBG ships the border on dt/dd with a
  :last-of-type reset, but the one-row-per-<div> grouping (for axe) made every
  dt/dd a last-of-type, stripping them all. Carry the separator on the row
  (:host:not(:last-of-type)) in the CIBG line colour (#f1f5f9 = cool-grey-200).
- Upload "Bestand toevoegen" button read as a pale outline: btn-outline-primary
  forced a transparent background over .btn-upload's accent fill. Use
  btn-primary btn-upload (solid #01689b, white text, folder glyph) and drop the
  redundant centred background-image folder.

GREEN: lint, tokens, 183 tests, build, 137 axe stories. Verified via Storybook
screenshots (datablock separators, filled blue upload button).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app/shared/ui/upload/file-input/file-input.component.ts

@@ -26,7 +26,9 @@ const TYPE_LABELS: Record<string, string> = {
     .file-picker-drop-area { display: flex; flex-direction: column; align-items: flex-start; gap: var(--rhc-space-max-sm); }
     /* Default (not subtle) foreground: subtle grey on the grey drop-area fails WCAG AA contrast. */
     .upload-instructions { margin: 0; color: var(--rhc-color-foreground-default); font-size: var(--rhc-text-font-size-sm); }
-    .btn-upload { cursor: pointer; }
+    /* Solid CIBG-blue button; the .btn-upload ::before folder glyph is the icon, so
+       drop its redundant centred background-image folder. */
+    .btn-upload { cursor: pointer; background-image: none; }
     .btn-upload.disabled { cursor: not-allowed; }
     /* The input is visually hidden but still focusable; surface its focus on the button. */
     input:focus-visible + .btn-upload { outline: var(--rhc-border-width-md) solid var(--rhc-color-foreground-link); outline-offset: 2px; }
@@ -48,7 +50,7 @@ const TYPE_LABELS: Record<string, string> = {
         [multiple]="multiple()"
         [disabled]="disabled()"
         (change)="onChange($event)" />
-      <label class="btn btn-outline-primary btn-upload" [class.disabled]="disabled()" [attr.for]="inputId()">
+      <label class="btn btn-primary btn-upload" [class.disabled]="disabled()" [attr.for]="inputId()">
         {{ buttonText() }}
       </label>
     </div>