VS Code: Allow submitting images without requiring text

Feature Request

When pasting an image into the Claude Code VS Code extension input, the submit button requires text to be entered before the message can be sent.

Sometimes an image alone is the entire prompt — e.g., pasting a screenshot for triage, a UI mockup for feedback, or an error screenshot. Having to type filler text ("see image", "^", etc.) just to unlock the submit button adds unnecessary friction.

Expected behavior: Pasting an image into the input should be sufficient to enable the submit button, even with no accompanying text.

Current behavior: The submit button remains disabled until text is also entered alongside the pasted image.