feat: refactor theme handling and update TODO.md

- Replaced references from theme-config to ui-config for better organization and clarity in theme management.
- Updated Solarized icon in ui-config to a pill emoji for improved visual representation.
- Marked the Solarized icon correction task as complete in TODO.md.
- Deleted the now redundant theme-config file to streamline the codebase.

src/lib/types.ts

@@ -1,5 +1,5 @@
 import { TfsConfig } from '@/services/integrations/tfs/tfs';
-import { Theme } from './theme-config';
+import { Theme } from './ui-config';
 
 // Réexporter Theme pour les autres modules
 export type { Theme };