feat: allow server-mode preview deploy trigger

[nichenqin]

Summary

• allow self-hosted server API mode to accept trusted pull-request preview context for deploy
• use server-provided deploymentHref/deploymentUrl when available and output deployment-url for workflows, step summaries, and PR comments
• keep preview route/profile/env/secret inputs rejected in server mode until the server owns that policy
• add public action CI dry-run coverage for the self-hosted preview deploy API path

Verification

• bash -n scripts/install-appaloft.sh scripts/run-deploy.sh scripts/resolve-control-plane.sh

Merge notes

• Merge after feat(action): allow self-hosted preview deploy trigger appaloft#181 lands, because this PR mirrors the wrapper source from the main repository.
• This updates main; moving the v1 tag still needs an explicit decision.