fix(transactions): the underlag column is one surface, not a dropzone and an orphan button (#1628)

* fix(transactions): the underlag column is one surface, not a dropzone and an orphan button

The Bokfor transaktion dialog stretched its empty dropzone into a
45/72vh well and pinned "Valj befintligt underlag" alone at the very
bottom of the column, visually disconnected from the dropzone it
belongs to.

- Empty state: the underlag column now sizes to its content and
  top-aligns; the inbox picker renders as a quiet full-width dashed
  row directly under the dropzone ("eller valj befintligt underlag
  fran inkorgen"), so drop-a-file and pick-from-inbox read as one
  intake surface. The fixed-height sticky column returns as soon as
  a document previews there (uploaded, picked, or pre-linked).
- Grid rebalanced from 1fr/520px to 2fr/3fr so the kontering side
  dominates while nothing is being previewed on the left.
- QuickReviewDialog gets the same footer-row treatment for its picker
  trigger inside the underlag collapsible, so both #1620 surfaces
  present the affordance identically (disabled-while-booking kept).

Presentation only: upload path, select-mode picker held until booking,
linkDocuments with inbox_item_id, picked-state resets on close and
transaction change, and duplicate-match wiring are all unchanged.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* docs: record the QuickReviewDialog picker-trigger consistency decision

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

components/transactions/QuickReviewDialog.tsx

@@ -663,17 +663,19 @@ export default function QuickReviewDialog({
                 {/* Locked while the booking is in flight: handleConfirm captured
                     pickedInboxDocs when it started, so anything picked now would
                     never be linked and would then be cleared on completion,
-                    vanishing from the list with no error to explain it. */}
-                <Button
+                    vanishing from the list with no error to explain it.
+                    Styled as the dropzone's footer (same treatment as
+                    TransactionBookingDialog) so upload and inbox-pick read as
+                    one underlag surface. */}
+                <button
                   type="button"
-                  variant="outline"
-                  size="sm"
                   disabled={isProcessing}
                   onClick={() => setInboxPickerOpen(true)}
+                  className="flex w-full items-center justify-center gap-2 rounded-lg border border-dashed border-muted-foreground/25 px-3 py-2 text-[13px] text-muted-foreground transition-colors duration-150 hover:border-primary/50 hover:text-foreground disabled:pointer-events-none disabled:opacity-50"
                 >
-                  <Inbox className="mr-2 h-4 w-4" />
-                  {t('doc_pick_existing')}
-                </Button>
+                  <Inbox className="h-4 w-4" />
+                  <span>{t('doc_pick_existing_inline')}</span>
+                </button>
               </div>
             )}
           </div>