fix: support windows and linux from package.json run

[zendril]

Running bun x opencode@opentui was giving error: interpreter executable "/bin/sh" not found in %PATH% when running bun x opencode-ai@opentui

The package.json bin was hardcoded to the linux ./bin/opencode
This puts a shim in place to figure out whether to execute ./bin/opencode or ./bin/opencode.cmd

[zendril]

I dunno why the script/format.ts is now failing.. seems to be confused about being on a branch.

[rekram1-node]

I just merged opentui branch into this to avoid confusion

[zendril]

Hold on before approving/merging.

It starts the TUI fine, but I think it isn't passing any args, so only the help shows no matter what args are passed.

[zendril]

updated with a change to opencode.cmd. args were not be parsed correctly in there.

Now it runs the TUI if no args and then runs the other args properly if passed.

[zendril]

anything else you need me to do/verify or are you waiting on other reviews?