feat(berths): active-interests popover + row-density toggle on berth list

Two complementary UX upgrades on the berth list:

1. Active-interests popover — replaces the plain "Active interests"
   count cell with a click-to-expand popover. Each row shows the
   linked deal's client name, pipeline stage (with stage-badge tint),
   and a primary-star icon. Lazy-loads on first open (30s stale),
   capped at 20 entries server-side, sorted most-recently-updated
   first. Backed by `GET /api/v1/berths/[id]/active-interests`.

2. Row-density toggle — DataTable gains a `density: 'comfortable' |
   'compact'` prop. Compact drops cell vertical padding from py-3 to
   py-1.5 so reps can scan many more berths per viewport on the
   high-density admin lists.

   Persisted alongside hidden-columns in `user_profiles.preferences.
   tablePreferences[entityType].density`. Hook returns `density +
   setDensity`; defaults to 'comfortable' for users who haven't
   chosen. The setter shares the same debounced PATCH with setHidden
   so toggling both doesn't multiply the network round-trips.

   Toolbar adds a Rows3/Rows4 icon button between the saved-views
   dropdown and the ColumnPicker. tooltip + aria-label flip to
   communicate the next state.

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

src/components/shared/data-table.tsx

@@ -82,6 +82,13 @@ interface DataTableProps<TData> {
    * needing a preferences migration.
    */
   columnVisibility?: VisibilityState;
+  /**
+   * Row density. `'comfortable'` (default) keeps shadcn's default
+   * cell padding. `'compact'` drops vertical padding so reps can scan
+   * more rows per viewport, useful for berth tables and admin lists.
+   * Affects desktop only — the mobile card list ignores it.
+   */
+  density?: 'comfortable' | 'compact';
   /**
    * Opt-in row virtualization. Only renders rows in the viewport (plus a
    * small overscan), so a 5000-row client-export list stays at 60 fps.
@@ -125,6 +132,7 @@ export function DataTable<TData>({
   cardRender,
   mobileGroupBy,
   columnVisibility,
+  density = 'comfortable',
   virtual,
   virtualHeightPx = 600,
   virtualRowHeightPx = 48,
@@ -312,7 +320,10 @@ export function DataTable<TData>({
                       onClick={() => onRowClick?.(row.original)}
                     >
                       {row.getVisibleCells().map((cell) => (
-                        <TableCell key={cell.id}>
+                        <TableCell
+                          key={cell.id}
+                          className={density === 'compact' ? 'py-1.5' : undefined}
+                        >
                           {flexRender(cell.column.columnDef.cell, cell.getContext())}
                         </TableCell>
                       ))}