docs: restore accurate claim that workflow skill dispatches both PR and deploy-dev workflows

[placerda]

Why

Reverts the false narrowing introduced by #211. A live recording of the
prompt-agent tutorial proved that the workflow skill dispatches both
agentops-pr.yml and agentops-deploy-dev.yml as part of its
end-to-end CI verification — not just the PR workflow. The skill uses
workflow_dispatch (which works against any branch regardless of the
workflow's push: block) and asks the user to approve first, per
SKILL.md rule #14.

PO's screenshot from the live recording showed:

Workflow	Run ID	Status
agentops-deploy-dev.yml	#26615996505	Stage ✅ · Cloud eval ran ✅ · Gate threshold_failed (exit 2 = by design)
agentops-pr.yml	#26616081824	Stage ✅ · Cloud eval ran ✅ · Gate threshold_failed (exit 2 = by design)

Both runs went all the way through stage → eval → deploy(summarize)
and bootstrapped versions into the dev Foundry project. The
threshold_failed exit on both is by design — when bootstrap
creates a fresh travel-agent:1 against the seed thresholds for the
first time, the eval can miss; that is CI wiring verification, not a
real regression.

What changes

docs/tutorial-prompt-agent-quickstart.md step 13:

• Replaces the PR docs: correct skill verification claim to PR workflow only #211 wording (triggered a first verification run of agentops-pr.yml (via workflow_dispatch) plus the
  agentops-deploy-dev.yml does not run yet paragraph) with a clear
  statement that the skill dispatched both workflows end-to-end.
• Adds the "by design" explanation for the threshold_failed exit on
  these first verification runs.
• Updates the "What you should see in the first PR workflow run"
  section away from the "dev is still empty" assumption (no longer
  true after the skill's verification dispatch) to the three possible
  outcomes (reused / created / bootstrapped) you can actually
  see at this point.
• Trims the redundant "On the second PR run" paragraph into a more
  general "successive PR runs" statement.
• Reframes the merge-triggered deploy as the second deploy-dev run
  for the repo (the first was the skill's verification dispatch in
  step 12).

CHANGELOG.md — [Unreleased] → Fixed entry.

Validation

• python -m pytest tests/ -x -q → 802 passed, 3 skipped (no code
  paths changed).
• All edits are inside docs/tutorial-prompt-agent-quickstart.md and
  CHANGELOG.md. No source or template changes.

Related

• Supersedes docs: correct skill verification claim to PR workflow only #211 (which was the false-narrowing).
• Builds on docs: deep audit of all three tutorials (8 procedural bugs) #212 (the 8-bug audit fix).