feat(scripts): enhance translation progress tool with CLI flags, TOML management, and CI-friendly output

[Ludy87]

Description of Changes

• What was changed

  • Refactored scripts/counter_translation.py into a more modular CLI tool.
  • Added argument parsing with new flags:
    • --lang/-l to check a single messages_*.properties file.
    • --show-percentage/-sp to print only the numeric percentage (useful for CI).
    • --show-missing-keys/-smk to list untranslated keys for a single language.
  • Introduced main() entrypoint and helper _lang_from_path() for robust language code extraction.
  • Improved comparison logic:
    • Skips header lines, trims values, and tolerates BOM.
    • Treats en_GB/en_US as 100% translated.
    • Tracks and reports missing keys; removes keys from ignore list once translated.
  • Hardened TOML handling:
    • Automatically creates/updates scripts/ignore_translation.toml when absent.
    • convert_to_multiline() normalizes/sorts arrays for stable diffs.
  • README integration:
    • write_readme() updates language badges from computed progress.
  • Added type hints, richer docstrings, usage examples, and clearer console messages.
  • Deduplicates language results and sorts by percentage (desc).
  • Uses consistent UTF-8 and newline handling.

• Why the change was made

  • Make translation tracking automation-ready (CI pipelines can consume a single number).
  • Reduce manual maintenance of ignore lists and improve deterministic formatting for clean diffs.
  • Provide better developer UX with explicit flags and actionable diagnostics (missing keys).
  • Increase correctness and maintainability via structured code, typing, and clear responsibilities.

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Checklist

General

• I have read the Contribution Guidelines
• I have read the Stirling-PDF Developer Guide (if applicable)
• I have read the How to add new languages to Stirling-PDF (if applicable)
• I have performed a self-review of my own code
• My changes generate no new warnings

Documentation

• I have updated relevant docs on Stirling-PDF's doc repo (if functionality has heavily changed)
• I have read the section Add New Translation Tags (for new translation tags only)

UI Changes (if applicable)

• Screenshots or videos demonstrating the UI changes are attached (e.g., as comments or direct attachments in the PR)

Testing (if applicable)

• I have tested my changes locally. Refer to the Testing Guide for more details.

[Copilot]

Pull Request Overview

This PR significantly refactors the translation counter script to improve documentation, add command-line argument support, and enhance maintainability. The script now supports checking individual language files and offers CI/CD-friendly output modes.

• Added argparse-based CLI with options for single file checking and percentage-only output
• Refactored main logic into a main() function and extracted language parsing to _lang_from_path()
• Enhanced documentation with comprehensive docstrings and usage examples

Comments suppressed due to low confidence (1)

scripts/counter_translation.py:199

• File is not explicitly closed. Use a context manager (with open(...)) to ensure proper resource cleanup.

    num_lines = sum(
        1
        for line in open(default_file_path, encoding="utf-8")
        if line.strip() and not line.strip().startswith("#")
    )

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