Fix addressed fields to use comma-separated strings

[cpinto]

Summary

• CreateReply and Messages.Create were sending addressed fields (directly, copied, blindcopied) as JSON arrays instead of comma-separated strings, causing 422 errors or silent draft creation
• Messages.Create originally used strings.Join correctly but was regressed in 495c2fb when CC/BCC support was added; CreateReply copied the broken pattern in c39876a
• Fixed both methods to use strings.Join(addrs, ",") matching the OpenAPI MessageAddressed spec (type: string)
• Fixed TestMessagesService_Create which was asserting the wrong type ([]any instead of string)
• Added entry.addressed validation to TestEntriesService_CreateReply which had none

Fixes basecamp/hey-cli#66

Test plan

• go build ./... compiles
• go test ./pkg/hey/... passes (both fixed tests validate string types)
• Manual: hey reply <thread-id> -m "test" sends without 422
• Manual: hey compose --to a@b.com --cc c@d.com sends without 422

🤖 Generated with Claude Code

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Summary by cubic

Fix addressed fields to send comma-separated strings for compose and reply, matching the API spec and preventing 422 errors or silent draft creation. Aligns behavior in both paths and resolves basecamp/hey-cli#66.

• Bug Fixes
  • CreateReply and Messages.Create now send directly, copied, and blindcopied as comma-separated strings (via strings.Join), per OpenAPI MessageAddressed (type: string).
  • Tests updated: fix expected types in TestMessagesService_Create and add addressed validation in TestEntriesService_CreateReply.

^{Written for commit 6d33c63. Summary will update on new commits.}

[Copilot]

Pull request overview

This PR fixes a bug where CreateReply and Messages.Create methods were sending recipient fields (directly, copied, blindcopied) as JSON arrays instead of comma-separated strings, which was causing API validation errors (422 responses). The fix updates both methods to use strings.Join() to properly format email addresses as comma-separated strings, and updates the corresponding tests to expect string types instead of arrays. Additional test coverage for the CreateReply method's addressed field is also added.

Changes:

• Fixed Messages.Create() to use strings.Join() for recipient fields
• Fixed Entries.CreateReply() to use strings.Join() for recipient fields
• Updated test assertions in TestMessagesService_Create to expect strings instead of arrays
• Added validation for recipient fields in TestEntriesService_CreateReply

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
go/pkg/hey/messages.go	Added strings import and updated Create() method to format recipient addresses as comma-separated strings
go/pkg/hey/entries.go	Added strings import and updated CreateReply() method to format recipient addresses as comma-separated strings
go/pkg/hey/services_test.go	Updated test assertions to expect string types and added missing validation for addressed field in CreateReply test

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[cubic-dev-ai]

No issues found across 3 files