docs: propose Kubernetes-native Mecatl operator

[JAORMX]

Summary

• Add a design proposal for a Kubernetes-native Mecatl operator under docs/drafts.
• Define platform, application-team, and end-user responsibilities across profiles, content, agent definitions, models, MCP, policy, structured memory, learning, execution, and automation.
• Specify publication, authorization, state ownership, recovery, and phased acceptance criteria. Keep sessions and other application state behind runtime APIs and backing stores.
• Use ASD-STE100 writing principles without claiming certified conformance. Link the proposal from the drafts index.

This PR contains documentation only. Resource declarations are illustrative, not implemented APIs. Remaining design decisions are listed explicitly.

Validation

• task docs:check passed, including instruction-file checks, the documentation example test, and strict matlatl checks with no broken links, anchors, or unreachable documents.
• git diff --check passed.
• Independent design/editorial review completed; findings addressed.
• Full documentation regeneration and broader code gates were interrupted; they are not claimed as passing.

API compatibility

No wire API, Go API, or stored-data changes. The proposal identifies future compatibility assessments for profile selection, entitlement enforcement, and durable publication bindings. It preserves reserved protobuf fields and requires explicit approval before any breaking implementation.