[AIAA] Build probe: first cloud-agent delegation (section 17 checks 1-5)

The spec's probe delegation (PR #363, section 16, as amended by
09a92bf): the first delegation to the cloud agent is a deliberately
disposable task whose real product is observed platform behavior. The
draft PR closes unmerged and links here; the answers are recorded below
against the spec's section 17 build-time checks and parameterize later
build steps.

Depends on: #364 (preflight gates every delegation to the cloud agent).

## Observations to record (section 17 build-time checks)

Prior evidence from cncf/mentoring's cloud-agent PRs (#1527, #1631,
#1668, Dec 2025 to Feb 2026) sets expectations for the first three
items; the platform may have changed since, so each is recorded fresh
here.

- [ ] Agent branch naming (head ref of the draft PR). Expected:
`copilot/`, three for three in cncf/mentoring.
Recorded:
- [ ] Whether delegation reliably opens a draft pull request (first
data point; confirmed again on every later delegation). Expected:
yes; in cncf/mentoring the agent opened a PR even when blocked,
using the body to ask for clarification.
Recorded:
- [ ] The agent token's effective scopes, best effort (session logs and
PR timeline: what the token demonstrably did or failed to do). If
not directly observable, record that with the behavioral
evidence. Prior evidence: mentoring #1631, asked to create
issues, reported "the necessary tools are read-only". The probe
prompt asks the agent to attempt a label write and report the
result.
Recorded:
- [ ] Whether Actions runs on the agent's PR wait for approval (Checks
tab: do format-check, link-check, and spell-check run on their
own or queue as "waiting for approval"?). No prior signal:
mentoring's agent PRs triggered no Actions workflows.
Recorded:
- [ ] What access review-comment revisions require (a writer requests a
change; someone without write access comments; note which the
agent acts on). Needs a volunteer without write access. No prior
signal: every mentoring commenter held write.
Recorded:

## Spec references

Section 16 probe delegation (as amended by 09a92bf); checks from
section 17; bound by P-1 (a human delegates, reviews, and closes). The
draft PR closes unmerged, per section 16: the observations, not the
diff, are the product.