fix: support clipboard image paste (Ctrl+V) on Windows

[ghost]

Summary

Fixes clipboard image paste not working on Windows when using Ctrl+V (e.g., after capturing a screenshot with Greenshot).

Problem

On Windows, pressing Ctrl+V with an image in the clipboard didn't paste the image because:

1. The terminal (ConPTY) doesn't properly send image data through bracketed paste events
2. Clipboard.read() was only called when the paste event text was empty
3. Windows terminals often send non-empty text or don't fire the paste event at all for clipboard images

Solution

Added explicit keybind handling in onKeyDown (in the prompt component) to:

• Intercept Ctrl+V before the terminal handles it
• Call Clipboard.read() directly to check for images in the clipboard
• If an image is found, paste it using pasteImage() and prevent default
• If no image is found, let the normal text paste flow continue

Testing

1. Use Greenshot (or any screenshot tool) to capture a region to clipboard
2. In OpenCode CLI, press Ctrl+V
3. The image should now be pasted as [Image 1] in the prompt

Changes

• packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx: Added keybind check for input_paste in onKeyDown handler

[rekram1-node]

/review

[github-actions]

lgtm

[nielpattin]

@zzzeian was something broken with the Greenshoot or with Windows Terminal that you can't paste image?

• Which terminal you using?
• Because right now(before this PR merged) in Wezterm or Alacritty can just default paste image just fine.
• Windows Terminal need to disable "Remove trailing white-space when pasting" in the setting.
• Are you using wsl?
• I'm using ShareX to capture image, not sure what happened with your.