Multiline copy truncates spaces between lines

### Describe the bug

Multiline drag selection & right click to copy truncates spaces around lines.

### Affected version

GitHub Copilot CLI 1.0.57-4

### Steps to reproduce the behavior

The example here is from a changelog, but the phenomenon appears in user prompt/agent responses too.

1. Prepare a multi-line text.

For example, `/changelog last 10`.

2. Drag and select multiline text, where the word

I'll select the sentence starting with "Context window tier..."

3. Right click to copy it

4. I get no spaces between "tier-dervied" and "limits"

> - Context window tier selection now persists durably in session events and survives SDK-only resume paths so tier-derivedlimits are reapplied to request, compaction, and truncation logic without app-level repair

### Expected behavior

Spaces are correctly preserved, so that copy-pasting keeps the original content

### Additional context

_No response_

Reproduce the issue in GitHub Copilot CLI 1.0.57-4 using the multiline selection and right-click copy steps, especially the changelog example containing “tier-derived limits.” Trace the CLI’s multiline selection and clipboard-copy path, then verify that copied text preserves spaces between lines and matches the selected content.

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