spec: add TEA discovery, protobuf, and JSON schema drafts

[MChorfa]

Summary

This PR carries forward only the specification-facing parts of the previous ref-impl branch.

Included here:

• discovery and API flow documentation
• TEA protobuf definitions under proto/tea/v1
• JSON schemas under schemas/json
• supporting spec-oriented diagrams and reference docs

Explicitly excluded from this PR:

• Rust server implementation
• Dagger/build automation
• CI/release/supply-chain workflows
• generated integration/reference-implementation material

Implementation split

The implementation work has been moved into a separate repository:

• https://github.com/MChorfa/transparency-exchange-reference-implementation

Notes

This is intended to align with the repository boundary discussed in the previous review and keep this PR limited to spec/schema/doc content.

[MChorfa]

Implementation work has been moved to a separate repository for review here:

• https://github.com/MChorfa/transparency-exchange-reference-implementation

This PR is now limited to specification-facing documentation, protobuf definitions, and JSON schemas. CI is currently green (DCO and GitGuardian both passing).

If a smaller review unit is preferred, I can split the remaining content further into separate docs/diagrams and proto/schema PRs.

[oej]

Please split this up into more focused PRs so we can discuss each separately. Thank you.

[oej]

A pull request this large requires a lot of time for the peers in the working group. We are getting close to 1.0 and are very resistant to add new things before the release. Splitting it up in smaller pieces, more focused, makes it easier to handle and accept small changes - like formatting - and take larger changes later.

The TLS requirements - are they written by you or an AI? It doesn't seem based on experience.

[MChorfa]

Following the request to split this into smaller review units, I have opened focused replacement PRs:

• 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
• doc: narrow TEA authentication guidance #236 doc: narrow TEA authentication guidance

I am closing this broader PR to reduce review load. If the remaining narrative docs and diagrams are still useful, I can reintroduce them later as separate focused PRs.

[MChorfa]

Following the request to split this into smaller review units, I have opened focused replacement PRs:

• 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
• doc: narrow TEA authentication guidance #236 doc: narrow TEA authentication guidance

I am closing this broader PR to reduce review load. If the remaining narrative docs and diagrams are still useful, I can reintroduce them later as separate focused PRs.