Fix chat dark mode

[AndyScherzinger]

Quick merge, to resolve the general issues with dark text on dark surface.

Resolves #6025

mentioning @mahibi for awareness

🏁 Checklist

• ⛑️ Tests (unit and/or integration) are included or not needed
• 🔖 Capability is checked or not needed
• 🔙 Backport requests are created or not needed: /backport to stable-xx.x
• 📅 Milestone is set
• 🌸 PR title is meaningful (if it should be in the changelog: is it meaningful to users?)

[github-actions]

APK file: https://github.com/nextcloud/talk-android/actions/runs/23984957257/artifacts/6272489815
To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud app.
(please click on link to get QR code displayed)

[github-actions]

APK file: https://github.com/nextcloud/talk-android/actions/runs/23985315339/artifacts/6272586377
To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud app.
(please click on link to get QR code displayed)

[github-actions]

Codacy

Lint

Type	master	PR
Warnings	90	90
Errors	0	0

SpotBugs

Category	Base	New
Bad practice	6	6
Correctness	10	10
Dodgy code	53	53
Internationalization	3	3
Malicious code vulnerability	3	3
Performance	4	4
Security	1	1
Total	80	80