docs: add Aegis governance integration to observability

[Acacian]

Summary

• Add Aegis observability/governance integration page (docs/en/observability/aegis.mdx)
• Add Korean translation (docs/ko/observability/aegis.mdx)
• Add Card to observability overview pages (en, ko)
• Add navigation entries to docs.json (en, ko, pt-BR, ar)

What is Aegis?

Aegis is an open-source governance runtime for AI agents.
It auto-instruments CrewAI (and other frameworks) to add:

• Prompt injection detection (107 patterns)
• PII masking (email, phone, SSN)
• Policy-as-code (YAML-based)
• Complete audit trail

PyPI: https://pypi.org/project/agent-aegis/

Note: This PR was generated with LLM assistance (label llm-generated requested but may not be available on this repository).

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Note

Low Risk
Documentation-only changes that add new pages and navigation links; no runtime or API behavior is modified.

Overview
Adds new Aegis governance integration documentation pages under Observability (including en, ar, ko, and pt-BR content) describing how to auto-instrument CrewAI and apply governance features like prompt-injection detection, PII masking, policy-as-code, and audit trails.

Updates the Observability overview pages to surface Aegis via a new card, and extends docs.json navigation so the new */observability/aegis pages appear in sidebars across the supported locales.

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