refactor(cmd): inject output stream

[synackd]

Description

Context

This is branch 8 of 16 in a stacked series (stack/coverage/01-exit-code-contract → stack/coverage/16-convention-checks) that replaces ochami's package-global CLI state with an invocation-scoped runtime, adds a regression test suite, makes the tests safe to run in parallel under Go's race detector, and enforces the test conventions in CI. It is stacked on stack/coverage/07-command-and-client-cleanup and merges before stack/coverage/09-http-client-foundations. Review each branch's own diff.

Branches

• stack/coverage/01-exit-code-contract
• stack/coverage/02-client-contract-tests
• stack/coverage/03-command-e2e-and-interactive
• stack/coverage/04-public-config
• stack/coverage/05-injected-boundaries
• stack/coverage/06-coverage-regressions
• stack/coverage/07-command-and-client-cleanup
• stack/coverage/08-output-and-error-injection ← THIS BRANCH
• stack/coverage/09-http-client-foundations
• stack/coverage/10-configfile-and-rcs-hardening
• stack/coverage/11-typed-batches-and-context
• stack/coverage/12-local-command-options
• stack/coverage/13-runtime-core-and-command-migration
• stack/coverage/14-test-parallelization-and-race-detection
• stack/coverage/15-final-coverage-closure
• stack/coverage/16-convention-checks

Summary

Route command output through the CLI's injected output stream (cli.Ios.Out()) instead of process-global stdout: service output, configuration display, version information, cloud-init data, and prompts. Callers and tests can capture output without replacing os.Stdout, and the command test harness no longer swaps it.

dialWebSocket returns the error from parsing a malformed console URI instead of ignoring it and dereferencing a nil URL, and ConnectConsole returns a failure to restore the terminal after an interactive session instead of discarding it.

.golangci.yml turns on errcheck's check-blank, so errors discarded with _ = are reported, and exempts the command flag getters (Flags().GetBool etc.), whose errors can't occur for flags registered with the matching type on the same command. Tests that discarded errors now check them. New discover-static and BSS error-arm tests live in _errors_test.go files, and pkg/discover, pkg/format, and pkg/xname get new tests.

Why

Writing to process-global stdout prevents capturing output per invocation and makes output assertions depend on swapping operating-system globals.

Review notes

Check that every migrated command writes to the injected stream. No output format or wording change is intended. Write failures are still ignored, as before.

Checklist

• My code follows the style guidelines of this project
• I have added/updated comments where needed
• I have added tests that prove my fix is effective or my feature works
• I have run make test (or equivalent) locally and all tests pass
• I have updated the relevant documentation (CLI examples, man pages, README, other docs, etc.)
• DCO Sign-off: All commits are signed off (git commit -s) with my real name and email
• REUSE Compliance:
  • Each new/modified source file has SPDX copyright and license headers
  • Any non-commentable files include a <filename>.license sidecar
  • All referenced licenses are present in the LICENSES/ directory

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Dependency update
• Build system/CI

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• I agree to follow the Code of Conduct.