docs: add opencode-goal-plugin to ecosystem

[william-ricchiuti]

Issue for this PR

N/A

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Adds opencode-goal-plugin to the ecosystem docs plugin list in packages/web/src/content/docs/ecosystem.mdx.

opencode-goal-plugin gives OpenCode a session-scoped /goal workflow that keeps the current objective in context and automatically continues work until the goal is complete, blocked, or a safety limit is reached.

Project links:

• GitHub: https://github.com/willytop8/OpenCode-goal-plugin
• npm: https://www.npmjs.com/package/opencode-goal-plugin

How did you verify your code works?

• Confirmed the docs entry was added to the Plugins table in packages/web/src/content/docs/ecosystem.mdx
• Verified the link target and description text match the plugin's published GitHub repo and npm package
• Confirmed this PR only adds the new ecosystem entry with no unrelated changes

Screenshots / recordings

N/A (docs-only change)

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

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