BUG: Webcam permission denial permanently blocks Face Detection using Webcam

## Description
When using Face Detection Search via Webcam, denying camera permission once puts the app into a permanent failure state with no way for the user to recover.

This makes the webcam based face search feature unusable for the rest of the session (and effectively for the user), even if they later want to allow camera access.

## Steps to Reproduce
1. Open PictoPy
2. Go to Face Detection Search on top in search bar
3. Click Use Webcam
4. When the Camera Access permission prompt appears (http://tauri.localhost wants to use your camera), click "Don’t Allow"
5. Observe behavior after denial

## Current Behavior

App repeatedly shows a popup modal:
```
Webcam Not Supported
Webcam is not supported or access was denied on this device.
Close
```
There is no way to retry permission. No other way is provided to re-enable camera access. Clicking “Use Webcam” again results in the same blocking popup. Webcam-based face detection becomes permanently unusable.

Video proof 👇

https://github.com/user-attachments/assets/3d76748e-369e-48eb-a930-2e8caae19611

## Expected Behavior

If camera access is denied:
- The app should not trap the user in a dead-end state
- Users should have a clear recovery path, such as:
- An option to retry camera access
- Clear instructions on how to re-enable permissions
- The error state should be informative and actionable, not terminal

This is **release critical for 1.1.0** as webcam based Face Detection is a core feature. A single accidental click on “Don’t Allow” permanently breaks it and can affects first time users.