feat(build): Improve error messages for nonexistent projects

[runningcode]

Summary

• Improve error messages when sentry-cli build upload fails due to nonexistent projects
• Provide specific guidance about using --project and --org flags
• Add integration test for nonexistent project scenario

Changes

• Enhanced error handling in src/commands/build/upload.rs to detect "Project not found" errors
• Added helpful guidance messages for users when project doesn't exist
• Created integration test command_build_upload_nonexistent_project with mock endpoints

Fixes EME-175

[linear]

EME-175 Missing error message on `sentry-cli mobile-app upload HackerNews.apk --project nonexistantproject`

[szokeasaurusrex]

@runningcode What's wrong with the existing output? If you run this code against master, you'll get an output like:

  WARN    2025-09-15 16:10:45.833138 +02:00 Failed to upload 1 file:
  WARN    2025-09-15 16:10:45.833274 +02:00   - tests/integration/_fixtures/build/archive.xcarchive (Project not found. Ensure that you configured the correct project and organization.)

This does not mention the specific flags, but given that there are multiple ways of specifying orgs and projects, and given that we use this same error message everywhere else in Sentry CLI, I am not sure we need to add a specific additional message only for the build commands.

EME-175 appears to have been opened before the error message was added to the warning line. I would argue that the general warning should be sufficient to resolve that issue.

[runningcode]

Yes you're right we don't need this PR. The error message was already improved on the backend.

The still existing bad message is when the org is non-existant though. I'll need to fix that.

The Sentry server lacks chunked uploading support, which is required for build uploads. If you are using a self-hosted Sentry server, update to the latest version of Sentry to use the build upload command.