Add policy template: Education/EdTech agent

[Acacian]

Summary

Add a pre-built policy template for education/EdTech AI agents. This would cover scenarios like student data access, grade modifications, and content generation.

What to do

1. Create examples/templates/education.yaml
2. Define rules for common EdTech agent actions:
   • Auto-approve: reading course materials, searching resources
   • Require review: accessing student records, modifying grades
   • Block: bulk data exports, deleting student records
3. Add a matching preset in src/aegis/presets/ if the pattern exists
4. Add a brief description to the templates section in docs

Context

Look at existing templates in examples/templates/ (healthcare, financial, etc.) for the structure to follow.

Acceptance criteria

• Template is valid YAML and loads without error
• Covers at least 6 rules across auto/approve/block
• Includes comments explaining each rule's purpose