Learning opportunities

### Objective
Implement the learning opportunitites plugin concept in opencode

### Context
Given the rise in the use of code agents to develop software projects, it is necessary to prevent students from engaging in superficial learning; therefore, using agents in teaching mode rather than for blind code generation seems beneficial in the long term

### Checklist

- [ ] Review the [learning opportunities](https://github.com/DrCatHicks/learning-opportunities) plugin of claude/codex
- [ ] Implement the learning opportunities plugin in opencode in skill mode or plugin mode

Start by reviewing the linked learning-opportunities plugin for Claude/Codex and determine how its concept maps to opencode. Then decide whether skill mode or plugin mode is appropriate. Done means the learning-opportunities concept is implemented in opencode and supports teaching-oriented agent use.

Written by the indexing model from the issue text.