copyToClipboard fires on single click without selection

[EugenEistrach]

Clicking on any terminal cell triggers SelectionManager.copyToClipboard, even when there's no text selected. This overwrites the user's clipboard with empty or single-character content unexpectedly.

The issue is in SelectionManager - copyToClipboard is called without checking if there's an actual selection (start cell ≠ end cell).

Proposed fix - check hasSelection() before copying:

async copyToClipboard(text: string) {
  if (!this.hasSelection()) {
    return;
  }
  // existing copy logic
}

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Note: This fix was developed during an AI-assisted session and is currently used as a monkey-patch in our application. Due to time constraints we're unable to submit a proper PR, but wanted to share the finding.