#2393 Docs: dashboard resume and opt-in auto-resume for manual approval gates (follow-up to #2377)

What changed

swamp-club#2377 changes how approved runs continue. There are two changes:

1. The dashboard can resume an approved run. A run that is approved but still suspended shows under Awaiting resume, on the Approvals page, the Overview Live Runs and the run detail, with a Resume button and the exact swamp workflow resume <workflow> --run <id> command. For a workflow that declares inputs, the command carries an --input <key>=<value> placeholder and a note that a dashboard resume supplies no new inputs.
2. Opt-in auto-resume. A workflow can set autoResume: true | false at the top level. swamp serve --auto-resume (SWAMP_AUTO_RESUME, serve.yaml auto-resume: true, default off) applies to workflows that declare no inputs and leave autoResume unset. A workflow with inputs must opt in itself, because it may rely on supplying real values at resume. When an approval made through serve decides a run's last gate, serve resumes the run itself. A local swamp workflow approve never triggers it. swamp workflow approve --server prints Serve is resuming run <id> automatically and returns autoResumed: true in JSON. A refused or failed auto-resume is logged and audited (workflow.auto_resume_failed), and the run stays awaiting resume.

Pages to update

• content/manual/how-to/gate-a-workflow-with-manual-approval.md:
  • Add approving and resuming from the dashboard.
  • Add a section on skipping the manual resume with autoResume: true or serve --auto-resume, including the input-less rule and a warning not to enable it on workflows that expect resume-time --input.
  • The suspend, approve, resume walkthrough stays correct for the default.
• content/manual/reference/workflows.md:
  • Document the top-level autoResume field (boolean, optional) and its precedence over the serve flag.
  • In the manual_approval section, note that auto-resume only happens for approvals made through serve.
• content/manual/reference/swamp-serve.md:
  • Add --auto-resume / SWAMP_AUTO_RESUME / auto-resume to the flag and config tables.
  • Describe the dashboard as a complete approve-and-resume surface.
  • Document the new workflow.approve response field autoResumed and the workflow.run.search item fields awaitingResume and workflowHasInputs.

The in-repo design docs (design/primitives/workflows.md, design/primitives/serve.md) and the swamp skill references are already updated in the same PR, and can be used as the source text.