[Feature] Dark mode #181

What outcome should OpenMuse handle?

Using the app comfortably when the environment or the device is set to dark. Today the app renders light-only on all platforms, so opening it at night — or on a device where every other app follows the system's dark setting — is a jarring, bright experience. I run a self-hosted instance and this is the one thing that keeps me from using it in the evening.

Proposed behavior

The app offers a dark appearance. Following the OS/browser setting by default would cover most users; a manual override in the UI would help people who want the app darker or lighter than their system. Chat, Activity, Ideas, Goals and the Apps screens would all need a readable dark palette.

How would we verify it works?

• Set the device or browser to dark appearance → all primary screens render in a dark palette with readable contrast.
• With the manual override, the app switches independent of the OS setting, and the choice persists across restarts.
• Behavior is consistent across web, iOS and Android.