add 'region' field support

[metachris]

📝 Summary

Builder instances can register a region field, which is returned to other builders as part of the peers info.

The region field can be registered as part of any service.

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Here's the e2e test snippet:

# [Builder API] Register credentials for 'orderflow_proxy' service
POST http://localhost:8888/api/l1-builder/v1/register_credentials/orderflow_proxy
{
  "ecdsa_pubkey_address": "0x321f3426eEc20DE1910af1CD595c4DD83BEA0BA5",
  "tls_cert": "abcdefghijklmnopqrstuvwxyz",
  "region": "europe"
}
HTTP 200

# [Builder API] Get the list of peers
GET http://localhost:8888/api/l1-builder/v1/builders
HTTP 200
[Asserts]
jsonpath "$.[0].orderflow_proxy.ecdsa_pubkey_address" == "0x321f3426eec20de1910af1cd595c4dd83bea0ba5"
jsonpath "$.[0].orderflow_proxy.tls_cert" == "abcdefghijklmnopqrstuvwxyz"
jsonpath "$.[0].orderflow_proxy.region" == "europe"

[Copilot]

Pull request overview

Adds end-to-end support for an optional region attribute on service credential registrations so it can be stored in Postgres and returned in peers/builder listings.

Changes:

• Extend domain + ports types to include region in service credentials and peer info payloads.
• Persist region in service_credential_registrations (schema migration + insert/select updates).
• Update E2E coverage (Go DB-backed test + Hurl script) to assert region round-trips.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
scripts/ci/e2e-test.hurl	Registers region and asserts it appears in peers output
schema/004_region.sql	Adds region column to service_credential_registrations
ports/types_test.go	Adds JSON unmarshal test coverage for region
ports/types.go	Adds Region to ServiceCred and maps domain -> ports
ports/http_handler.go	Passes region through the register-credentials handler/service interface
httpserver/e2e_test.go	DB E2E asserts region persists and is returned
domain/types.go	Adds Region to domain.BuilderServices
application/service.go	Threads region through application interfaces
adapters/database/types.go	Maps DB credential -> domain including region
adapters/database/service.go	Writes/reads region to/from Postgres

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