Closes #45179

## Summary

Fixes the focus behavior when creating terminals with
`RevealStrategy::NoFocus` or `RevealStrategy::Never`. Previously,
terminals would still receive focus if the terminal pane already had
focus, contradicting the documented behavior.

## Changes

- **`add_terminal_task()`**: Changed focus logic to only focus when
`RevealStrategy::Always`
- **`add_terminal_shell()`**: Same fix

The fix changes:
```rust
// Before
let focus = pane.has_focus(window, cx)
    || matches!(reveal_strategy, RevealStrategy::Always);

// After  
let focus = matches!(reveal_strategy, RevealStrategy::Always);
```

## Impact

This affects:
- Vim users running `:!command` (uses `NoFocus`)
- Debugger terminal spawning (uses `NoFocus`)
- Any programmatic terminal creation requesting background behavior

Release Notes:

- Fixed terminal focus behavior to respect `RevealStrategy::NoFocus` and
`RevealStrategy::Never` settings when the terminal pane already has
focus.