fix(explore): name the propose workflow at every handoff (#1788)

* fix(explore): name the propose workflow at every handoff

Explore mode refuses to implement, but nowhere named the workflow that
turns the discussion into a change. The refusal, the "flow into a
proposal" ending, the closing summary, and the do-not-implement
guardrail all described the next step as prose. With no named exit,
agents answered the discovery questions and then started writing code
(#869).

All four handoff points now point at `/opsx:propose`, written in the
canonical `/opsx:<id>` form so each tool renders the invocation it
actually registers. Skill and command bodies are patched together, the
skills.sh mirror is regenerated, and parity hashes are refreshed.

Closes #869

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* fix(explore): name the continuation after a seamless capture

The capture path let explore scaffold a change and write artifacts, then
said nothing about what came next. An agent holding a fresh proposal
inside explore mode has an obvious wrong next move, and it is the one
#869 reported. The capture now ends by naming `/opsx:propose` for the
remaining planning artifacts and `/opsx:apply` for implementation, and
says plainly that capturing artifacts is not permission to implement
them.

Widen the rendering guard to walk the real registries instead of a
hand-picked few: every registered command adapter and every entry in
AI_TOOLS must rewrite every canonical reference in both bodies, with no
`/opsx:` form surviving on any skills surface. A new adapter or a
changed invocation shape now fails here rather than shipping a command
nobody answers to.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* docs(changeset): cover the capture-path handoff

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* fix(explore): resolve handoffs against the installed workflow set

A custom profile can install explore without propose or apply, and the
explore skill and command still named both. Handoffs are now authored with
optionalWorkflow() and resolved in getSkillTemplates()/getCommandTemplates()
against the workflow filter every init/update path already passes. Missing
workflows fall back to explore's own capture path and the openspec
instructions apply CLI. Output with every workflow installed is unchanged.

Uses the same API and marker syntax as #1775 so the two compose.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* docs(changeset): drop em dashes from the release note

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

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Co-authored-by: Claude Opus 5 <noreply@anthropic.com>