Forwarded email aliases are generated immediately upon viewing the page, rather than after confirming

### Steps To Reproduce

1. Go to "Generator"
2. Click "Username"

### Expected Result

Alias should only be generated after clicking a button to confirm.

### Actual Result

Alias will be immediately generated upon viewing the page, which can accidentally generate/save a bunch of unused aliases at the service every time you click generator. It makes it really hard to tell what aliases are real and which are garbage that Bitwarden generated when I didn't need it.

### Screenshots or Videos

_No response_

### Additional Context

The browser extension functions properly, and requires clicking the "generate" button to generate the initial alias, in order to prevent cluttering up the alias service. By default, the alias field simply says `-`.

I am specifically using Addy.io, but I suspect the behavior is the same on any service.

### Build Version

2025.12.0

### What server are you connecting to?

Self-host

### Self-host Server Version

Vaultwarden 1.36.0

### Environment Details

N/A

### 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 reproducing the issue in the iOS Generator flow after selecting Username, then trace where the initial alias is requested when the page is viewed. Compare the behavior with the browser extension, where the field remains '-' until Generate is confirmed. Done means viewing the page creates no alias and confirming generation creates one as expected.

Written by the indexing model from the issue text.