[WIP]feat(i18n): add tool to detect unused translation keys

[RoyLee1224]

Why

As the Airflow UI grows, translation files accumulate keys that are no longer used in the source code. This tool helps developers maintain the cleanliness of translation files.

Note: I'm marking this as a draft since this is just the first phase. The code has not yet been refactored, and the detection logic still needs some improvement. Feedback and discussion are welcome!

Key Features

1. Static Analysis: Scans .ts and .tsx files in airflow/ui to find usages of translate().
2. Dynamic Key Support:
   • Task/DAG states (e.g., state.${taskState} expands to state.success, state.failed, etc.).
   • Directions (up, down, etc.).
3. Pluralization Handling: Recognizes that using a base key implies usage of its plural forms (task_one, task_other).
4. Documentation: Updated dev/breeze/doc/breeze_ui.rst and added the command output screenshot.

Implementation Details

• The script uses Regex to parse translation keys.
• It compares the keys defined in en/*.json against the keys found in the source code.
• It reports:
  • Unused: Defined in JSON but not found in code.
  • Undefined: Used in code but missing in JSON.
  • Dynamic Patterns: Lists detected dynamic template literals.

Screenshots

I've verified that these keys in admin.json and assets.json are indeed unused. (For nameMaxLength, it's a key mismatch.)

The detection logic for dynamic key in common.json still needs some refinement. However, I can confirm that at least keys like allOperators and logicalDateFrom are unused and should be removed.

While the detection isn't 100% precise yet, it effectively isolates the potential candidates. Finding these unused keys manually would have been nearly impossible.

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