Self-Review Checklist:**

- [x] I've reviewed my own diff for quality, security, and reliability
- [ ] Unsafe blocks (if any) have justifying comments
- [ ] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [ ] Tests cover the new/changed behavior
- [X] Performance impact has been considered and is acceptable

## What

When terminal cursor shape is set via escape sequences (e.g. `\e[6 q`
for bar, `\e[4 q` for underline), the cursor looks identical whether the
terminal is focused or unfocused. Block cursors already convert to a
hollow outline when unfocused, but bar and underline were missing this
treatment.

## How

Added unfocused guards for `Beam` and `Underline` in the cursor shape
match in `terminal_element.rs`, converting them to `Hollow` when the
terminal loses focus. This follows the same pattern already used for
`Block`.

## Why this approach

A hollow block outline is the clearest unfocused signal and stays
consistent with the existing Block behavior. Alternative approaches like
dimming opacity or drawing outlined versions of bar/underline were
considered, but a 2px-wide outlined bar would be nearly invisible at
normal font sizes.

## Demo:
Before: 


https://github.com/user-attachments/assets/81d49899-0837-42fe-a68f-4eb745892af6

After:


https://github.com/user-attachments/assets/a4444e28-5835-4c9f-872f-e9ce8c4805a0


Closes #52716

Release Notes:

- Fixed terminal bar and underline cursors set via escape sequences not
visually distinguishing between focused and unfocused states