* fix(settings): reject failed provider diagnostics

The diagnostic dispatch discarded the CLI exit code and accepted any parsed response without a nonempty error message. Reuse the shared command outcome classifier, preserve the previous normalized diagnostic on failure, and report existing localized process errors.

Add executed regressions through the production dispatch and completion handlers; migrate the existing fixture to pass its process exit code. Update Unreleased and the usage guide. No TODO parity entry or new CLI contract is affected.

* fix(settings): preserve diagnostic fetch failure reports

Released Linux CLI 0.74.1 exits successfully with a schema 1.0 diagnostic report whose error field describes a failed provider fetch. The generic configuration command classifier rejected those useful reports.

Add a diagnostic-specific classifier that preserves valid report data while retaining process-exit and command-envelope validation. Reproduce object and array reports through production completion, test the pure interface, and verify an isolated official CLI report. Update usage, Unreleased, and the reordered translation template. No TODO parity entry is completed.