feat(i18n): add Kazakh (kk, kk-KZ) localization by @HmnDev-Tech

[HmnDev-Tech]

Summary

This PR adds full Kazakh (values-kk / values-kk-rKZ) language localization for the Essentials app.

Changes Made

• Added strings.xml with translated strings for Kazakh localization under the appropriate resource directory.
• Verified that all key identifiers match the default (values/strings.xml) language resource file.
• Validated formatting, escaped characters, and string placeholders (%s, %d) to prevent runtime XML parsing issues.

Motivation

Adding native Kazakh language support improves accessibility and user experience for Kazakh-speaking Android users.

Testing & Validation

• Ran the local validation script (python3 scripts/validate_strings.py) to verify syntax, character escaping, and placeholder integrity.
• Tested the app with the system language set to Kazakh to confirm all localized strings load correctly without fallback errors.

[sameerasw]

I need to do some further testing for this translations as they should be switchable from the language picker as well should be available for the in-app translation features. Will test and review soon.