spec: add TEA publisher and insights service drafts

[MChorfa]

Summary

This PR is a focused split from #235.

It contains only the remaining service-level protobuf drafts for:

• proto/tea/v1/publisher.proto
• proto/tea/v1/insights.proto

Scope

This follow-up intentionally excludes:

• shared data model and discovery/consumer contracts already split into spec: add TEA discovery and consumer contract drafts #237
• authentication and profile notes already split into doc: narrow TEA authentication guidance #236 and doc: add a short TEA profiles note #238
• narrative docs, diagrams, and graph schema

Intent

Keep review centered on the publisher and insights service surfaces only.

[MChorfa]

This PR is one part of the split from #235, which has been closed in favor of smaller review units.

Related PRs:

• doc: narrow TEA authentication guidance #236 doc: narrow TEA authentication guidance
• spec: add TEA discovery and consumer contract drafts #237 spec: add TEA discovery and consumer contract drafts
• doc: add a short TEA profiles note #238 doc: add a short TEA profiles note
• spec: add TEA publisher and insights service drafts #239 spec: add TEA publisher and insights service drafts
• doc: add TEA narrative drafts #240 doc: add TEA narrative drafts
• doc: add TEA diagrams and graph schema #241 doc: add TEA diagrams and graph schema

[oej]

Our data structures main specification is in the openapi spec. What would adding this code add to our work?