refactor(profiles): drop manual snapshot update now that switching autosaves

Since switching projects automatically saves the current configuration
back to the project being left, the per-project "update from current"
button is redundant and even harmful: it allowed overwriting another
project's snapshot with the current state, breaking the invariant that
a project holds the state you last left it in.

- Remove the resnapshot button and confirm dialog from the manage
  dialog; drop the now-unused scope prop and PROFILE_SCOPE_LABELS
- Add a footer Close button to the manage dialog (overlay click is
  disabled app-wide, so it previously could only be closed via Esc)
- Update manageDescription in all four locales to describe the
  autosave behavior; remove the two dead i18n keys
- Fix a shadowed `warnings` vec in ProfileService::apply that silently
  dropped autosave-failure warnings before they reached the frontend
- Mention auto-capture on next switch in the "no snapshot for this
  scope yet" warning and doc comments

The backend update command keeps its resnapshot parameter; it is now
only exercised by the pre-switch autosave path.

src/i18n/locales/en.json

@@ -1883,11 +1883,9 @@
     },
     "manage": "Manage projects…",
     "manageTitle": "Manage Projects",
-    "manageDescription": "Projects are configuration snapshots. To change a project, adjust your configuration first, then click \"Update from current\".",
+    "manageDescription": "Projects are configuration snapshots. When you switch projects, the current configuration is automatically saved back to the project you are leaving.",
     "namePlaceholder": "e.g. Development, Drawing",
     "rename": "Rename",
-    "updateSnapshot": "Update from current",
-    "updateSnapshotConfirm": "Overwrite the {{group}} side of project \"{{name}}\" with the current configuration? Other apps' snapshots are unaffected.",
     "noSnapshotForScope": "Not saved for this app yet",
     "delete": "Delete",
     "deleteConfirmTitle": "Confirm Delete",

src/i18n/locales/ja.json

@@ -1883,11 +1883,9 @@
     },
     "manage": "プロジェクトを管理…",
     "manageTitle": "プロジェクト管理",
-    "manageDescription": "プロジェクトは設定のスナップショットです。内容を変更するには、先に設定を調整してから「現在の状態で更新」をクリックしてください。",
+    "manageDescription": "プロジェクトは設定のスナップショットです。プロジェクトを切り替えると、現在の設定は元のプロジェクトに自動的に保存されます。",
     "namePlaceholder": "例：開発、イラスト",
     "rename": "名前を変更",
-    "updateSnapshot": "現在の状態で更新",
-    "updateSnapshotConfirm": "プロジェクト「{{name}}」の {{group}} 側スナップショットを現在の設定で上書きしますか？他のアプリ側には影響しません。",
     "noSnapshotForScope": "このアプリ側は未保存",
     "delete": "削除",
     "deleteConfirmTitle": "削除の確認",

src/i18n/locales/zh-TW.json

@@ -1855,11 +1855,9 @@
     },
     "manage": "管理專案…",
     "manageTitle": "管理專案",
-    "manageDescription": "專案是設定快照。要修改專案內容，先手動調好設定，再點「以目前狀態更新」。",
+    "manageDescription": "專案是設定快照。切換專案時，目前設定會自動儲存回原專案。",
     "namePlaceholder": "例如：開發、繪圖",
     "rename": "重新命名",
-    "updateSnapshot": "以目前狀態更新",
-    "updateSnapshotConfirm": "用目前設定覆蓋專案 \"{{name}}\" 的 {{group}} 側快照？其他應用側的快照不受影響。",
     "noSnapshotForScope": "本側未儲存",
     "delete": "刪除",
     "deleteConfirmTitle": "確認刪除",

src/i18n/locales/zh.json

@@ -1883,11 +1883,9 @@
     },
     "manage": "管理项目…",
     "manageTitle": "管理项目",
-    "manageDescription": "项目是配置快照。要修改项目内容，先手动调好配置，再点\"以当前状态更新\"。",
+    "manageDescription": "项目是配置快照。切换项目时，当前配置会自动保存回原项目。",
     "namePlaceholder": "例如：开发、绘图",
     "rename": "重命名",
-    "updateSnapshot": "以当前状态更新",
-    "updateSnapshotConfirm": "用当前配置覆盖项目 \"{{name}}\" 的 {{group}} 侧快照？其他应用侧的快照不受影响。",
     "noSnapshotForScope": "本侧未保存",
     "delete": "删除",
     "deleteConfirmTitle": "确认删除",