fix(ui): humanize enum labels, format dates, resolve actor names, loading skeleton

- Documents hub signer status now renders via a label map (`Pending`,
  `Signed`, `Declined`, …) instead of the raw lowercase enum value.
- Invoice detail formats `dueDate` and `paymentDate` as `MMM d, yyyy`
  via `date-fns` instead of leaking raw `2025-03-14` ISO strings, and
  swaps the "Payment Method" free-text input for a `Select` of labelled
  options (`Bank transfer`, `Credit card`, …) so we never store
  `bank_transfer` from a hand-typed field again.
- Interest tabs `MilestoneSection` status badge uses a `humanizeStatus`
  helper so values like `waiting_for_signatures` show as
  `Waiting For Signatures` (correctly title-cased) instead of being a
  lower-snake-case fragment inside an ALL-CAPS pill.
- `OUTCOME_BADGE` in the interest header now has a fall-through that
  renders any unknown outcome as a closed-state badge, preventing a
  closed interest from looking open just because its enum was added
  upstream without a matching label entry.
- Interest timeline route joins the `user` table and returns
  `userName` alongside `userId`; the client renders the resolved name
  instead of a 36-char UUID. Falls back to `'a teammate'` if the user
  row was deleted.
- Invoice "New / Step 3 — Review" replaces the truncated UUID display
  with a server-resolved client/company name via a small `useQuery`,
  so users can confirm they picked the right billing entity before
  submitting.
- New `loading.tsx` for client detail renders a header / tab strip /
  card skeleton during the server-component / initial-query window
  that previously flashed empty.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/documents/documents-hub.tsx

@@ -74,6 +74,15 @@ const STATUS_PILL_MAP: Record<string, StatusPillStatus> = {
   rejected: 'rejected',
 };
 
+const SIGNER_STATUS_LABELS: Record<string, string> = {
+  pending: 'Pending',
+  sent: 'Sent',
+  signed: 'Signed',
+  declined: 'Declined',
+  expired: 'Expired',
+  cancelled: 'Cancelled',
+};
+
 interface DocumentsHubProps {
   portSlug: string;
   initialTab?: DocumentsHubTab;
@@ -187,7 +196,7 @@ export function DocumentsHub({ portSlug, initialTab = 'all' }: DocumentsHubProps
                     <span className="truncate text-muted-foreground">{signer.signerEmail}</span>
                   </div>
                   <StatusPill status={STATUS_PILL_MAP[signer.status] ?? 'pending'}>
-                    {signer.status}
+                    {SIGNER_STATUS_LABELS[signer.status] ?? signer.status}
                   </StatusPill>
                 </li>
               ))}