web: base custom instance functionality

also:
- renamed processing tab in settings to "instances"
- improved override description
- prefer custom over override (and grey out the option)
- dedicated lib for all api safety warnings
- left aligned small popup with smaller icon
- ability to grey out settings category & toggle

web/src/lib/api/api.ts

@@ -3,7 +3,7 @@ import { get } from "svelte/store";
 import settings from "$lib/state/settings";
 import { getSession } from "$lib/api/session";
 import { currentApiURL } from "$lib/api/api-url";
-import { apiOverrideWarning } from "$lib/api/override-warning";
+import { apiOverrideWarning } from "$lib/api/safety-warning";
 
 import type { Optional } from "$lib/types/generic";
 import type { CobaltAPIResponse, CobaltErrorResponse } from "$lib/types/api";