Summary

Follow-up to #3701. This PR addresses remaining consistency issues in Traditional Chinese (zh_TW) translations:

• Fix environment-related translations: The key environment maps to "Variable Groups" in English, but some related keys (askDeleteEnv, enterEnvJson, environment_required) were incorrectly using "環境" (environment) instead of "變數群組" (variable group). Now uses "變數群組" for Variable Group context, and "環境變數" for actual environment variables.
• Standardize "新xx" to "新增xx": All action-oriented labels like "New Project", "New Template", "New Key" etc. now consistently use "新增" (add/create) prefix instead of bare "新" (new), which is the standard convention in Taiwan UI design.
• Keep "Playbook" untranslated: Replaced "劇本" with "Playbook" as it is a well-known Ansible technical term that Taiwan users expect to see in English.
• Standardize "覆蓋" to "覆寫": Use "覆寫" consistently for "override" across all translations.
• Standardize "（可選）" to "（選填）": Use "選填" to pair naturally with "必填" (required), following Taiwan form UI conventions.
• Fix "表達式" to "表示式": Use the standard Taiwan term for "expression".

Test plan

• Switch UI language to Traditional Chinese and verify translated strings on all pages
• Confirm "新增" prefix appears consistently on all "New ..." dialog titles and buttons
• Verify environment / variable group related pages use correct terminology