Add agent repos & container agent operations best practice

Comprehensive guide covering task submission to the agent-runtimes
control plane, available harnesses, monitoring, multi-model workflows,
agent repo forks with workspace layout, and artifact extraction patterns.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

BESTPRACTICES.md

@@ -26,3 +26,5 @@ Generalised best practices extracted from real project work via the `/distill-be
 - [API Design](api-design.md) — Transport security, auth (OAuth2/JWT/mTLS), versioning, pagination, error handling, idempotency, rate limiting, input validation, zero-trust patterns
 - [Octopus Process Templates](octopus-process-templates.md) — OCL syntax, step template references, channel scoping, parameters, versioning, Platform Hub patterns
 - [LLM Code Security](llm-code-security.md) — Security vulnerabilities in AI-generated code: injection flaws, hardcoded secrets, hallucinated packages, over-permissive defaults, IaC risks, crypto mistakes, review checklist
+- [CI Container Builds](ci-container-builds.md) — Registry cache with inline metadata, buildx in DinD, layer ordering, pip caching, scheduled base images
+- [Agent Repos & Container Agents](agent-repos.md) — Task submission, harnesses, monitoring, multi-model workflows, agent repo forks, workspace layout, artifact extraction