fix: revert to single-click service filter, show all services by default, page size 24

- Revert +/- buttons on service pills back to single-click = filter only this service
- Remove default exclusion of Exchange/SharePoint/Teams (privacy controls handle this server-side)
- Change default page size from 25 to 24 (divisible by 3 for the 3-column grid)
- Update DEFAULT_PAGE_SIZE config default to 24

backend/config.py

@@ -61,7 +61,7 @@ class Settings(BaseSettings):
     REDIS_URL: str = "redis://localhost:6379/0"
 
     # UI defaults
-    DEFAULT_PAGE_SIZE: int = 25
+    DEFAULT_PAGE_SIZE: int = 24
 
 
 _settings = Settings()