site: step reference pages don't exist; CLI surface undocumented

[pskry]

site: step reference pages don't exist; CLI surface undocumented

CLAUDE.md and CONTRIBUTING.md both mandate step reference pages under
site/content/docs/steps/. That directory does not exist; site content
is 5 files total. The only field-level step docs are the CLI-embedded
ones (scampi index <step>, generated from struct tags) - and scampi index itself is documented nowhere.

What exists on the site is accurate (every published code sample runs
clean against the current binary; transcripts match renderer output),
so this is a coverage problem, not a correctness one.

Gaps

• No step reference pages for any of the 15 kinds.
• Undocumented commands: index, inspect, secrets, fmt,
  version (test is described conceptually but never shown).
• Undocumented flags: --ascii, --color, --only, --targets.
• posix.source_remote/posix.source_target and ssh.target's
  optional fields (port, key, insecure, timeout,
  max_sessions) never mentioned.
• internal/std/container/container.scampi:28 declares
  image: string = "" (effectively optional) but the Go config tags it
  as required (internal/step/container/container.go:74). Pick one.

Fix

• Generate site/content/docs/steps/ from the same source as
  scampi index (struct tags via engine.IndexAll), so the pages
  can't drift. One page per kind.
• Rules invariant: every registered kind has a site page (mirrors
  the CLAUDE.md mandate).
• Document the CLI surface: commands + global flags.
• Resolve the container image optionality mismatch.
• Document target optional fields.

[pskry]

Ruling from today's session: dedicated step reference pages under site/content/docs/steps/ are deliberately DEFERRED until the step surface stabilizes - scampi index is the canonical per-step reference for now, and no doc points at the site pages anymore (the CLAUDE.md mandate was rewritten accordingly). What remains actionable in this issue: documenting the CLI surface (index, inspect, secrets, fmt, --ascii, --color, --only, --targets), the container image optionality mismatch, and the target optional fields.

[pskry]

Correction to my earlier comment: scampi index is being DELETED entirely (#450) - the std stubs are the canonical per-step reference now. What remains actionable here shrinks to: documenting the CLI surface (inspect, secrets, fmt, --ascii, --color, --only, --targets), the container image optionality mismatch, and the target optional fields on the site.