feat(i18n): add hardcoded string detection script and CI check

[DeJeune]

What this PR does

Before this PR:

• Hardcoded Chinese/English UI strings could be introduced without detection
• No automated way to identify strings that need internationalization

After this PR:

• Added a script (scripts/check-hardcoded-strings.ts) to detect hardcoded UI strings
• Integrated into CI workflow to check for hardcoded strings on PRs
• Fixed multiple hardcoded strings across the codebase with proper i18n keys

Why we need it and why it was done in this way

The following tradeoffs were made:

• The detection script uses pattern matching which may have false positives, but it's better to catch potential issues and manually review than to miss hardcoded strings

The following alternatives were considered:

• Manual review only - rejected because it's error-prone and doesn't scale

Breaking changes

None

Special notes for your reviewer

• The script can be run locally with pnpm i18n:hardcoded
• Added tests for the detection patterns in scripts/__tests__/check-hardcoded-strings.test.ts

Checklist

• PR: The PR description is expressive enough and will help future contributors
• Code: Write code that humans can understand and Keep it simple
• Refactor: You have left the code cleaner than you found it (Boy Scout Rule)
• Upgrade: Impact of this change on upgrade flows was considered and addressed if required
• Documentation: Not required for this change

Release note

Add automated detection of hardcoded UI strings with CI integration

[EurFelux]

CI failed