feat: add agent-governance-toolkit template

[phala-agent]

Summary

• Add a Phala Cloud prebuilt template for microsoft/agent-governance-toolkit.
• Upstream repository: https://github.com/microsoft/agent-governance-toolkit
• Template files: templates/prebuilt/agent-governance-toolkit/docker-compose.yml, templates/prebuilt/agent-governance-toolkit/README.md, templates/config.json
• Icon: agent-governance-toolkit.svg; source documented in the README.

Environment variables

• See the template README for optional provider/runtime environment variables. No real secrets are included.

Validation

• python sdks/templates/validate.py
• git -C sdks diff --check origin/main...HEAD
• docker compose -f sdks/templates/prebuilt/agent-governance-toolkit/docker-compose.yml config >/dev/null
• static audit: README coverage, config ID uniqueness, icon file, forbidden compose directives, host bind mounts, and secret-like literals

Deployment smoke

• Deployed with phala deploy --profile hermes-admin-cvm-check --instance-type tdx.small --node-id 12 --wait --no-public-logs --no-public-sysinfo
• Smoke CVM: e005b2f5-556a-482c-86a6-33d46aab07cd
• Smoke app: 44770f308d8a2e14b1cbc993ace96811fae23dfb
• Endpoint probe: https://44770f308d8a2e14b1cbc993ace96811fae23dfb-8080.dstack-pha-prod7.phala.network/healthz -> 200 906 0.110293 rc=0
• Cleanup: temporary smoke CVM deletion requested and verified separately.

cc @Marvin-Cypher for review.

[phala-agent]

cc @Marvin-Cypher for review.