Description

Complete Dutch (nl) localization for app/src/main/res/values-nl/strings.xml. The existing partial Dutch file was expanded from 357 to 561 entries to match the base values/strings.xml coverage, including Cashu/payment strings, notification strings, mesh service strings, favorites/accessibility, chat headers, file viewer, about sheet settings, APK sharing/preparation, hotspot, install, and background-location explanations. Existing translations preserved; new translations use natural Netherlands Dutch (nl-NL). XML comments from the base file (license/info sections) are retained. No source logic changed.

Checklist

• I have read the contribution guidelines: https://github.com/permissionlesstech/bitchat-android?tab=readme-ov-file#contributing
• I have performed a self-review of my code
• I have mentioned the corresponding issue and the relevant keyword (e.g., "Closes: #xy") in the description (N/A — no linked issue for this localization update)
• If it is a core feature, I have added automated tests (not applicable — localization only)