i18n: zh_CN: unify terminology, fix mistranslations, and improve consistency across UI strings

[nkh0472]

Summary of changes

This PR improves the quality and consistency of the Simplified Chinese (zh_CN) translation for VeraCrypt. The changes are summarized below in order of importance/frequency:

---

1. Terminology unification (most frequent, ~40+ entries)

Inconsistent terms	Unified to
挂载 / 装载 / 安装 (for volumes)	加载 (Mount)
卷 / 加密盘 / 容器 (for file-hosted volumes)	加密卷 (Volume)
卸载 / 解除安装 (for drivers/apps)	卸载 (Uninstall/Unmount as appropriate)
Mount (options/menus)	加载
Unmount (options/menus)	卸载
外部的 / 外层的 / 外部卷	外层加密卷 (Outer Volume)
Boot Loader	启动管理器 (Boot Loader) — previously mixed with 引导器/加载程序
急救盘	应急盘 (Rescue Disk) — previously mixed with 救援盘

---

2. Format consistency (~20+ entries)

• Menu paths unified to “菜单名”->“子菜单” (was mixing →, -, >)
• Numbered steps unified to 1） 2） 3） with Chinese parentheses
• Brackets, quotes, and dashes unified to full-width Chinese punctuation
• Consistent handling of \n\n and spacing between Chinese/English text

---

3. Mistranslation corrections (~15 entries)

Original	Corrected
首密钥	头密钥 (Header Key)
首密钥离散算法	头密钥衍生算法 (Key Derivation Algorithm)
加密盘 (repeated)	加密卷 (Volume)
释放 (Extract context)	释放/解压 (context-dependent)
运行库 (Library)	运行库 — unified, was mixed with 动态库/库文件
安全口令牌	安全令牌/口令牌 — unified usage

---

4. Long-sentence simplification (~10 entries)

• Error messages and usage instructions with overly long compound sentences were split into shorter, independent clauses.
• Redundant modifiers (e.g. 非常, 很, 相当) removed.
• Passive voice converted to active voice where appropriate for better Chinese readability.

---

5. New strings (3 entries)

Translated 3 new warning strings related to EFI/Secure Boot, with terminology consistent with the rest of the translation.

---

Additional notes

• Changes were verified against the English source strings to ensure accuracy.
• Strings that were already correct or where the user's proposed change introduced inaccuracies were reverted (see individual review comments for details).
• All translations aim to maintain professional, clear, and unambiguous language suitable for security-critical software.