feat(workspace): add no-folder empty states and gate folder-only actions

- Sidebar: replace the "no conversations" placeholder with Open Folder, Clone Repository, and Project Boot buttons when the workspace has no open folders.
- Title bar: disable the terminal and auxiliary-panel toggle buttons while no folder is active.
- Aux panel: show a shared localized "no folder open" prompt in the file tree, git changes, and git log tabs when no folder is active.
- Add auxPanel.noFolderTitle / noFolderHint translations across all ten supported locales.

src/i18n/messages/ar.json

@@ -935,7 +935,9 @@
         "files": "الملفات",
         "changes": "التغييرات",
         "commits": "الالتزامات"
-      }
+      },
+      "noFolderTitle": "لا يوجد مجلد مفتوح",
+      "noFolderHint": "افتح مجلدا لعرض محتواه هنا"
     },
     "windowControls": {
       "minimizeWindow": "تصغير النافذة",

src/i18n/messages/de.json

@@ -935,7 +935,9 @@
         "files": "Dateien",
         "changes": "Änderungen",
         "commits": "Einträge"
-      }
+      },
+      "noFolderTitle": "Kein Ordner geöffnet",
+      "noFolderHint": "Öffnen Sie einen Ordner, um seinen Inhalt hier zu sehen"
     },
     "windowControls": {
       "minimizeWindow": "Fenster minimieren",

src/i18n/messages/en.json

@@ -935,7 +935,9 @@
         "files": "Files",
         "changes": "Changes",
         "commits": "Commits"
-      }
+      },
+      "noFolderTitle": "No folder open",
+      "noFolderHint": "Open a folder to see its contents here"
     },
     "windowControls": {
       "minimizeWindow": "Minimize window",

src/i18n/messages/es.json

@@ -935,7 +935,9 @@
         "files": "Archivos",
         "changes": "Cambios",
         "commits": "Confirmaciones"
-      }
+      },
+      "noFolderTitle": "No hay carpeta abierta",
+      "noFolderHint": "Abre una carpeta para ver su contenido aquí"
     },
     "windowControls": {
       "minimizeWindow": "Minimizar ventana",

src/i18n/messages/fr.json

@@ -935,7 +935,9 @@
         "files": "Fichiers",
         "changes": "Changements",
         "commits": "Validations"
-      }
+      },
+      "noFolderTitle": "Aucun dossier ouvert",
+      "noFolderHint": "Ouvrez un dossier pour voir son contenu ici"
     },
     "windowControls": {
       "minimizeWindow": "Minimiser la fenêtre",

src/i18n/messages/ja.json

@@ -935,7 +935,9 @@
         "files": "ファイル",
         "changes": "変更",
         "commits": "コミット"
-      }
+      },
+      "noFolderTitle": "開いているフォルダがありません",
+      "noFolderHint": "フォルダを開くとここに表示されます"
     },
     "windowControls": {
       "minimizeWindow": "ウィンドウを最小化",

src/i18n/messages/ko.json

@@ -935,7 +935,9 @@
         "files": "파일",
         "changes": "변경사항",
         "commits": "커밋"
-      }
+      },
+      "noFolderTitle": "열린 폴더 없음",
+      "noFolderHint": "폴더를 열면 여기에 표시됩니다"
     },
     "windowControls": {
       "minimizeWindow": "창 최소화",

src/i18n/messages/pt.json

@@ -935,7 +935,9 @@
         "files": "Arquivos",
         "changes": "Alterações",
         "commits": "Confirmações"
-      }
+      },
+      "noFolderTitle": "Nenhuma pasta aberta",
+      "noFolderHint": "Abra uma pasta para ver seu conteúdo aqui"
     },
     "windowControls": {
       "minimizeWindow": "Minimizar janela",

src/i18n/messages/zh-CN.json

@@ -935,7 +935,9 @@
         "files": "文件",
         "changes": "变更",
         "commits": "提交"
-      }
+      },
+      "noFolderTitle": "暂无打开的文件夹",
+      "noFolderHint": "打开一个文件夹后在这里查看"
     },
     "windowControls": {
       "minimizeWindow": "最小化窗口",

src/i18n/messages/zh-TW.json

@@ -935,7 +935,9 @@
         "files": "檔案",
         "changes": "變更",
         "commits": "提交"
-      }
+      },
+      "noFolderTitle": "尚無開啟的資料夾",
+      "noFolderHint": "開啟一個資料夾後可在此查看"
     },
     "windowControls": {
       "minimizeWindow": "最小化視窗",