feat(hook): support OpenCode 2.0 plugin format

[jchuder]

Summary

• Add OpenCode 2.0 plugin compatibility to hooks/opencode/rtk.ts via default export { id, setup }, hooking execute.before (tool) and create.before (shell).
• Maintain backward compatibility for OpenCode 1.0 via RtkOpenCodePlugin named export and server property.
• Switch command execution to node:child_process execFile to eliminate dependency on $ shell interpolation and prevent shell injection.
• Closes rtk init generates incompatible plugin format for OpenCode v2 #3898

Test plan

• cargo fmt --all && cargo clippy --all-targets && cargo test
• Verified test_opencode_plugin_dual_compatibility_v1_and_v2 unit test in src/hooks/init.rs
• Verified plugin module structure matches OpenCode 2.0 plugin contracts

[CLAassistant]

All committers have signed the CLA.

[Xefreh]

Thank you for this clean fix, any eta to merge this?

[Jiajun0413]

Thank you for this clean fix, any eta to merge this?感谢您解决了这个问题。那么，合并这个更改的预计时间是多少呢？

Same question.

[jchuder]

Hi @KuSh , do you have time to review this PR?

A few users have asked about its merge status. Please let me know if you need any changes from me.

Thanks!

[jchuder]

I am closing this PR in favor of #4187.

#4187 now covers the OpenCode 2.0 compatibility issue more completely, including exit code 3 handling, Windows support, binary resolution, and runtime tests.

Thanks to everyone who tested and followed up on this issue. Further work on this issue will be tracked in #4187.