[FEATURE]: Accept Alt+V for image pasting by default

[awakecoding]

Feature hasn't been suggested before.

• [x] I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

OpenCode currently only accepts Ctrl+V for image pasting by default, when both Claude Code and Copilot CLI accept Alt+V. Ctrl+V is problematic on Windows because Windows Terminal captures Ctrl+V by default without forwarding it to OpenCode, causing many users to incorrectly conclude that image pasting is not supported by OpenCode, as seen in https://github.com/anomalyco/opencode/issues/1429

I approached the Windows Terminal developers about this, and the default Ctrl+V behavior in WT was a contentious issue back in 2019. One can change the default configuration to remove the Ctrl+V keybinding from WT, but I don't think that's a good solution, since you need to be aware that it's there and preventing image pasting from working in OpenCode:

Rather than change the default (Ctrl+V), I suggest simply adding Alt+V, the same shortcut supported by Claude Code and Copilot CLI. Since Alt+V is not captured by Windows Terminal, there's no configuration change required. Users trying common key combinations that work for image pasting in other tools will likely try Alt+V, and conclude that image pasting works in OpenCode.

For discoverability, it wouldn't hurt to add an visual hint for image pasting, such as a ccamera emoji (📸: Alt+V), but I would consider the visual indicator or hint a separate feature request.