[client] feat(i18n): Add Galician (gl) localization for desktop client (#7041)

* Add Galician (gl) localization for desktop client

* [client] Address review feedback and sync latest i18n keys for Galician

Fix terms per review feedback (usarase, creen, auditar, JWT cache, poscuántico, etc.) and translate newly added upstream i18n keys.

* [client] Fix translations, polish terminology, and sync latest keys for Galician

* [client] Fix i18n parity against branch source of truth and drop undeclared uk

* [ci] Skip Galician locales in codespell check

* [client] Add latest error keys for Galician and revert _index.json formatting

Add error.settings_locked and error.settings_managed_by_mdm to Galician locale for 100% key parity with en/common.json. Revert multi-line formatting in _index.json to keep a single-line entry for Galician.

client/ui/i18n/locales/_index.json

@@ -10,6 +10,7 @@
         {"code": "it", "displayName": "Italiano", "englishName": "Italian"},
         {"code": "pt", "displayName": "Português", "englishName": "Portuguese"},
         {"code": "zh-CN", "displayName": "简体中文", "englishName": "Simplified Chinese"},
-        {"code": "ja", "displayName": "日本語", "englishName": "Japanese"}
+        {"code": "ja", "displayName": "日本語", "englishName": "Japanese"},
+        {"code": "gl", "displayName": "Galego", "englishName": "Galician"}
     ]
 }