[v3-1-test] Improve translation completeness checker (required keys, coverage, unused) (#62983) (#63307)

* Improve translation completeness checker: required keys, coverage, unused

- Required keys: EN base + plural forms for locale when EN has {{count}}
- Merge Extra and Unused into single Unused (keys not required)
- Table: Required (base EN), Required (plural), Total required, Translated,
  Missing, Coverage (translated/total), TODOs, Unused
- Coverage uses only real translations (exclude TODO placeholders)
- Rename --remove-extra to --remove-unused; remove_unused_translations()
- Update docs, SKILL, README, and help SVG

* Add translation:pt-BR section to boring-cyborg config

* Revert "Add translation:pt-BR section to boring-cyborg config"

This reverts commit dda93a9ef391741157ce150d2bf2d1256da198d6.

* Apply ruff format to ui_commands.py

* Update breeze docs: regenerate check-translation-completeness output

* Update ui_commands.py



* fix(breeze): translation checker row style (red for missing keys)

Fix unreachable red branch in style logic: use red for missing keys,
yellow for todos/unused, bold green when all clear. Also remove
unused missing_counts param and rename extra_keys to unused_keys.

---------
(cherry picked from commit 69257f04ee0d62e6e3a25996fb24d033143cc7df)

Co-authored-by: André Ahlert <andre@aex.partners>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>