Icon Cache Invalidated By Change Password URL Cache?

### Steps To Reproduce

1. Self-host Bitwarden
2. Add a new item with a Website URL with valid favicon
3. Reload the Bitwarden client, eventually the icon disappears

### Expected Result

Valid icons stay correctly cached so they show up correctly in the client.

### Actual Result

Icons randomly disappear off some items.

### Screenshots or Videos

_No response_

### Additional Context

I tried to track down why this is occurring, and I can't say for sure, but I think it is to do with a shared Memory Cache between the IconController and ChangePasswordUriController in the Icons server component.

In [server/src/Icons/Startup.cs](https://github.com/bitwarden/server/blob/8bd4af7a382c6a242dbae002110bcab0773c6066/src/Icons/Startup.cs#L43-L46)

```
// Cache
services.AddMemoryCache(options =>
{
options.SizeLimit = iconsSettings.CacheSizeLimit;
});
services.AddMemoryCache(options =>
{
options.SizeLimit = changePasswordUriSettings.CacheSizeLimit;
});
```

AddMemoryCache is called twice, but I'm not sure that calling this twice actually adds a separate memory cache to each controller instance. I'm not even sure iconsSettings.CacheSizeLimit ever gets used, as I think it is overwritten by the changePasswordUriSettings.CacheSizeLimit

Both the ChangePasswordUriController and IconsController use the same key (the domain) to cache values for the result. I am pretty sure that IconsController caches an icon successfully, then the ChangePasswordUriController runs, gets a null result and caches that null result.....overwriting the icon.

I created a patched version that uses a unique key in each controller, when accessing the MemoryCache, and the issue seems resolved.

e.g.
```
var mappedDomain = "Icon-" + _domainMappingService.MapDomain(domain);
var mappedDomain = "ChangedPasswordUri-" + _domainMappingService.MapDomain(domain);
```

### Build Version

2026.4.2

### Environment

Self-Hosted

### Environment Details

- Ubuntu 26.04 with podman

### Issue Tracking Info

- [x] I understand that work is tracked outside of Github. A PR will be linked to this issue should one be opened to address it, but Bitwarden doesn't use fields like "assigned", "milestone", or "project" to track progress.

Start by reading server/src/Icons/Startup.cs and the IconsController and ChangePasswordUriController cache access described in the issue. Verify whether the two AddMemoryCache registrations share a cache and whether both controllers use the domain as a key. Done means icon entries remain available after reload without being replaced by change-password URI results.

Written by the indexing model from the issue text.