i18n: Add placeholder locale entries for new subscription/teamWorkspacesDialog keys across non-English locales

## Context

PR #9901 (https://github.com/Comfy-Org/ComfyUI_frontend/pull/9901) added the following new i18n keys to `src/locales/en/main.json` but they are not yet present in the non-English locale files:

### New keys added

**`subscription.*`** (6 keys):
- `plansForWorkspace`
- `personalWorkspace`
- `teamWorkspace`
- `soloUseOnly`
- `needTeamWorkspace`
- `inviteUpTo`

**`teamWorkspacesDialog`** (9 keys — entire new block):
- `title`
- `subtitle`
- `subtitleNoWorkspaces`
- `confirmCallbackFailed`
- `yourTeamWorkspaces`
- `switch`
- `newWorkspace`
- `namePlaceholder`
- `createWorkspace`
- `nameValidationError`

**`workspaceSwitcher`** (1 key):
- `failedToSwitch`

### Affected locale files

`src/locales/ar/main.json`, `src/locales/es/main.json`, `src/locales/fa/main.json`, `src/locales/fr/main.json`, `src/locales/ja/main.json`, `src/locales/ko/main.json`, `src/locales/pt-BR/main.json`, `src/locales/ru/main.json`, `src/locales/tr/main.json`, `src/locales/zh/main.json`, `src/locales/zh-TW/main.json`

## Why

vue-i18n falls back to English so there is no user-facing breakage, but adding English-value placeholder entries lets translators discover and translate the new strings.

## Work

Add English-value placeholder entries for all 16 missing keys to each of the 11 non-English locale files listed above. This is mechanical work best done in a dedicated followup PR.

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Requested by @christian-byrne in https://github.com/Comfy-Org/ComfyUI_frontend/pull/9901#discussion_r2945814480

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-10210-i18n-Add-placeholder-locale-entries-for-new-subscription-teamWorkspacesDialog-keys-a-3266d73d365081cf94e8f43299ed3fb4) by [Unito](https://www.unito.io)