koKR : Update koKR translations and add missing strings

[Crazyyoungs]

What does this PR do?

Updates and refines the Korean (koKR) localization for UI and notification settings. Missing or untranslated Korean text strings have been newly added, and existing awkward translations have been corrected to align with standard WoW terms. This improves clarity and readability for Korean players using the addon configuration menu.

How was it tested?

• Tested in-game by loading the addon in the Korean client (koKR) and opening the configuration options panel to verify that all newly added and updated Korean texts display correctly without errors.

Checklist

• New settings default OFF (no behavior change without opt-in)
• Zero cost while disabled: no events registered, no polling, no hooks doing work, no frames built
• Cheap while enabled: event-driven (no polling, no timer-based logic, no per-frame allocations)
• No writes onto Blizzard-owned frames (weak-table pattern used); HookScript/hooksecurefunc only, never SetScript on Blizzard frames
• Tested in-game, works on live retail; no load errors on the 12.1 PTR client