feat(cli): add structured output to list commands

[mrunalp]

Summary

Add consistent table, json, and yaml output to forward list and the remaining literal list commands so automation can consume typed records without parsing human-oriented tables. Existing table output remains the default and retains its current behavior.

Related Issue

Closes #3066

Changes

• Add -o/--output <table|json|yaml> to service, policy, attached-provider, workspace-member, and forward lists.
• Return typed, empty structured collections without ANSI styling or prose; preserve full policy metadata and normalized service URLs.
• Keep attached-provider output secret-safe by exposing only sorted credential and config key names.
• Add CLI parsing, serializer, secret-safety, table-compatibility, empty-collection, and forward integration coverage.
• Update published CLI documentation and the openshell-cli skill reference.

Testing

• mise run pre-commit passes
• cargo test -p openshell-cli passes after rebase (446 passed, 2 existing ignored tests, 0 failed)
• Unit tests added/updated
• CLI integration tests added/updated
• mise run docs passes (0 errors)
• E2E tests not applicable; this changes client-side rendering only and does not change gateway or sandbox behavior

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs not applicable; command behavior is documented in the published CLI pages and skill reference

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[mrunalp]

/ok to test 440e90b