test: add tests for plugin tool execution hooks

[kynnyhsap]

Summary

The tool.execute.before and tool.execute.after plugin hooks lack test coverage. These hooks are critical for plugin developers who want to intercept and modify tool executions.

Problem

Currently, there are no automated tests verifying:

• Hooks receive correct input parameters
• Hooks can modify tool arguments (before) and results (after)
• Hooks can throw to block execution (before)
• Multiple hooks are called sequentially
• Edge cases like no hooks registered

Solution

Add comprehensive tests for both hooks covering all use cases.

Files to add

• packages/opencode/test/plugin/tool-hooks.test.ts

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• [BUG] Plugin hooks (tool.execute.before) don't intercept subagent tool calls - security policy bypass #5894: [BUG] Plugin hooks (tool.execute.before) don't intercept subagent tool calls - security policy bypass
• [FEATURE]: Expose tool execution capabilities to plugins #9056: [FEATURE]: Expose tool execution capabilities to plugins
• [FEATURE]: add tool.execute.error hook to handle tool call errors #10027: [FEATURE]: add tool.execute.error hook to handle tool call errors

These issues are related to plugin tool execution hooks and may share overlapping test coverage requirements or expose related functionality gaps that should be considered when adding tests.

Feel free to ignore if none of these address your specific case.