feat(clients): tidier bulk action toolbar

When at least one client is selected, the toolbar now collapses to a
small selection indicator plus the three most-used actions instead of
spreading six count-suffixed buttons across the row:

- Replaces every per-button "(N)" with a single closable "{N} selected"
  tag on the left — one click on its × clears the selection.
- Hides "+ Add Clients" while a selection is active (focus mode).
- Keeps Attach, Detach, and Delete as visible buttons; Delete is pushed
  to the right with auto margin so it doesn't sit flush against the
  non-destructive actions.
- Folds Adjust, Group, and Sub links into the existing "more"
  dropdown, which is now context-aware: selection-scoped overflow when
  rows are picked, global actions (Add Bulk / Reset all / Del depleted)
  otherwise.

On mobile the new buttons collapse to icon-only the same way as the
rest of the toolbar.

web/translation/en-US.json

@@ -542,6 +542,10 @@
       "assignGroupPlaceholder": "Group name (leave blank to clear)",
       "assignGroupAssignedToast": "Assigned {count} client(s) to {group}",
       "assignGroupClearedToast": "Cleared group from {count} client(s)",
+      "attach": "Attach",
+      "adjust": "Adjust",
+      "subLinks": "Sub links",
+      "selectedCount": "{count} selected",
       "attachSelected": "Attach ({count})",
       "attachToInboundsTitle": "Attach {count} client(s) to inbound(s)",
       "attachToInboundsDesc": "Attaches the selected {count} client(s) (same UUID/password and shared traffic) to the chosen inbound(s). They keep their existing attachments too.",

web/translation/fa-IR.json

@@ -513,6 +513,10 @@
       "deleteConfirmContent": "این کلاینت از تمام اینباندهای متصل حذف و سابقه ترافیک آن پاک می‌شود. این عمل غیرقابل بازگشت است.",
       "deleteSelected": "حذف ({count})",
       "adjustSelected": "تنظیم ({count})",
+      "attach": "اتصال",
+      "adjust": "تنظیم",
+      "subLinks": "لینک‌های ساب",
+      "selectedCount": "{count} انتخاب‌شده",
       "attachSelected": "اتصال ({count})",
       "attachToInboundsTitle": "اتصال {count} کلاینت به اینباند(ها)",
       "attachToInboundsDesc": "{count} کلاینت انتخاب‌شده (با همان UUID/پسورد و ترافیک مشترک) به اینباند(های) انتخابی متصل می‌شوند. روی اینباندهای فعلی هم باقی می‌مانند.",