refactor(localization): extract hardcoded localization texts into JSON and load via rust-i18n(#3537)

[hongqitai]

Summary

Ref #3537
Follow-up of #3549, #3559

• Extract hardcoded localization texts from crates/tui/src/localization.rs to crates/tui/locales
• Add crate rust-i18n to load localization texts
• Next step: use rust-i18n::t! macro to replace manual string concatenation
• If you think rust-i18n is a wrong way, merge crates/tui/locales only

Testing

• [ x ] cargo fmt --all -- --check
• [ x ] cargo clippy --workspace --all-targets --all-features
• [ x ] cargo test --workspace --all-features

Checklist

• [ x ] Updated docs or comments as needed
• [ x ] Added or updated tests where relevant
• [ x ] Verified TUI behavior manually if UI changes
• [ x ] Harvested/co-authored credit uses a GitHub numeric noreply address

[Hmbown]

Thanks for taking on the localization extraction. This is a broad refactor plus a new runtime dependency, so I’m going to keep it out of the late 0.8.65 release lane until the checks are fully green and we have more room to review the i18n shape.

Current blocker: macOS fails in commands::plugins::tests::test_plugins_empty_directory at crates/tui/src/commands/plugins.rs:215 because the emitted message no longer contains the canonical empty plugin directory path. Windows was cancelled after that failure. The likely fix is to preserve the path interpolation in the localized/plugin empty-directory message, then rerun the TUI test job.