Duplicate segment names allowed, causing confusion during linking

### How are you running Flagsmith

- [x] Self Hosted with Docker
- [ ] Self Hosted with Kubernetes
- [x] SaaS at flagsmith.com
- [ ] Some other way (add details in description below)

### Describe the bug

Currently, Flagsmith allows creating multiple segments with the same name within a project. This can lead to confusion when users link segments to features or environments, as they cannot easily distinguish between segments with identical names.

### Impact
- Increases risk of linking the wrong segment
- Degrades user experience and clarity
- Makes auditing and managing segments harder

### Suggested Fix
- Enforce unique segment names per project
**OR**
- Display disambiguating information (e.g., ID, created date) when listing segment options

### Steps To Reproduce

1. Create a segment with a name (e.g., `beta_users`).
2. Create another segment with the same name.
3. Attempt to link a segment to a feature or environment.

### Expected behavior

Users should be warned or restricted from creating duplicate segment names to prevent confusion.

### Screenshots

Duplicate Segments in Segment Page:

Duplicate Names in Feature Segment Override Section causing confusion"