Introduce i18n support and add English/Chinese language files; replace hardcoded UI strings

[juewuy]

Motivation

• Centralize user-facing strings and add localization to support English and Chinese for better maintainability and multilingual use.
• Replace scattered hardcoded prompts/messages with language keys so future translations and consistency improvements are easier.

Description

• Added new language files under scripts/lang/chs and scripts/lang/en for modules including bot_tg, check_port, ddns, providers, set_crashdir, subconverter, task_cmd, and uninstall to provide localized string variables.
• Updated menus and service scripts (for example scripts/menus/bot_tg.sh, bot_tg_bind.sh, bot_tg_service.sh, check_port.sh, ddns.sh, providers*.sh, set_crashdir.sh, subconverter.sh, task_cmd.sh, and uninstall.sh) to load_lang and replace hardcoded text with the corresponding language variables.
• Ensured i18n.sh is sourced where required and replaced cron/job naming and logger messages with localized variables (for example the TG bot cron name and log messages).
• Preserved original control flow and behavior while converting UI text to use localization keys and updated button/menu payloads in the Telegram bot menus to use the new variables.

Testing

• No automated tests were executed as part of this change.

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Codex Task

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Keep uninstall startup marker non-localized

Using $UNINSTALL_CRON_INIT as the deletion pattern means uninstall depends on the active UI language, but the startup hook inserted during install is still written with a fixed Chinese marker in scripts/init.sh (#ShellCrash初始化脚本). In English mode this sed expression won’t match, so the boot script entries in /etc/storage/started_script.sh and /jffs/.asusrouter are left behind and ShellCrash can still be invoked after uninstall on those platforms.

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