Normalize output-format parsing and rendering across builtin commands

[Sneh30]

What

Fixes #172: unify -f/--format parsing and rendering so every builtin command accepts and honors the same set of output formats, rejects unsupported values, and emits consistent structured output.

Single source of truth

• src/command-surface.ts now owns the canonical formats (table, plain, json, yaml, md, csv), the aliases yml → yaml and markdown → md, the shared help text, and the parseOutputFormat/resolveOutputFormat validators (case-insensitive).
• All -f/--format flags (builtin commands, auth status/refresh, adapter/hosted surfaces) advertise the same format list.

Behavior fixes

• plugin list -f yaml now emits real YAML (previously a table); empty plugin list -f json emits [] instead of human guidance.
• skills list, external list, plugin catalog list/add, plugin search, convention-audit, and auth status/refresh now honor all six formats with the correct explicit/implicit semantics (table in TTY, YAML outside TTY unless -f is given).
• webcmd list, skills list, convention-audit, plugin commands, and auth reject unsupported formats (e.g. -f xml) with a usage error (exit 2) instead of silently rendering a table.
• Aliases (yml, markdown) and case (-f YAML) are accepted and normalized everywhere.

Docs

• docs/cli-reference.mdx and skills/webcmd-usage/SKILL.md updated to reflect the shared format behavior, rejection of unknown formats, aliases, and plugin list -f json → [].

Testing

• npm test: 5191 passed, 1 skipped (12 new tests).
• npm run build OK; check:hosted-contract contract bytes unchanged; check:typed-error-lint 0 new.

[github-actions]

🟢 No documentation gap found — medium confidence

The automated review found no documentation gap in the supplied changes.

This review is advisory and does not block merging.