Terminal: dead-key shortcut no longer fires when terminal is focused (regression in 1.132.0)

The accent character is inserted into the shell instead. The same keybinding still works when an editor has focus.

**Does this issue occur when all extensions are disabled?:** Yes

- VS Code Version: 1.132.0 (Universal) and later. Last working version: 1.131.0 (Each version was tested from a clean download against the same user profile, so this is not caused by settings or keybindings.)
- OS Version: macOS 15.7.9.

### Version bisect

| Version | Result |
| --- | --- |
| 1.131.0 | works |
| 1.132.0 | broken |
| 1.133.0 | broken |
| 1.134.0 | broken |

Steps to Reproduce:

1. Use a keyboard layout with dead keys (I use a swedish keyboard), where `´` is a dead key.
2. Open the integrated terminal and focus it.
3. Press the Create Terminal keybinding (cmd+shift+´).

Expected: a new terminal opens.

Actual: a backtick is written into the shell. The keybinding never fires.

The same keybinding works correctly when an editor has focus. Only the terminal is affected.

### Keyboard Shortcuts Troubleshooting output

```
[KeybindingService]: / Soft dispatching keyboard event
[KeybindingService]: \ Keyboard event is part of an IME composition
[KeybindingService]: + Ignoring single modifier shift due to it being pressed together with other keys.
```

Soft dispatch returns early on the composition check, so the keybinding is never resolved and the character falls through to the shell. On macOS a dead key is surfaced as an IME composition, which is why this only affects dead-key layouts.

- `terminal.integrated.commandsToSkipShell` and `terminal.integrated.sendKeybindingsToShell` have no effect, since the resolver never runs.
- No user-facing setting works around this.

Possibly related: #282752 (dead-key shortcuts broken on Linux since 1.107.0).