feat(opencode): new plugin hook, command.execute.before

[rektide]

What does this PR do?

This PR proposes a command.execute.before, which allows for plugins to perform dynamic behavior & modification of command runs, including stopping their regular execution flow.

I have opened a discussion on the discord for this as well:
https://discord.com/channels/1391832426048651334/1458986650184060978

How did you verify your code works?

I've been slow to go deep testing this, and doing so has kept me from making a PR or draft. But I saw a call to action, with Dex talking about skills and commands and even though it sort of seems un-wise / a sore topic at the moment, I wanted to share & get this out here.

I'm doing more testing now.

Bikeshed rename for symmetry

I also have a commit in here to rename command.executed to command.execute.after, which makes squares this PR with what see see for tool hooks, which have tool.execute.before / tool.execute.after. I opted to retain command.executed as a hook too, for backwards compatibility stake, but "deprecated" it. This commit is in no way loadbearing, but I appreciate the symmetry it offers!

[github-actions]

Hey! Your PR title New Plugin Hook: command.execute.before`` doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Found potential duplicate:

• PR add command.execute.before hook + allow parallel subtasks + fix model inheritance #6478: add command.execute.before hook + allow parallel subtasks + fix model inheritance

This PR appears to be directly related or potentially a duplicate. It specifically mentions implementing the command.execute.before hook, which is the exact same feature being proposed in PR #7400. This earlier PR likely already addresses the same functionality.

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

See CONTRIBUTING.md for details.