[AIAA] Build step 1: workflow labels in .github/settings.yml

[nate-double-u]

First build step of the AI-assisted TechDocs assessment system (spec:
PR #363, section 16, step 1, as amended by 09a92bf). Copilot CLI drafts
a labels-only change to .github/settings.yml locally; the operator
pushes and opens the PR; humans review it, with Copilot code review as
an additional reader; a human merges. The platform observations this
step used to carry moved to the probe delegation (spec section 16),
which waits on #364. This step does not: locally drafted steps do not
wait on preflight.

Related: #364 (preflight; gates the probe delegation, not this step).

Deliverable

The assessment workflow labels added to the labels: block, alongside
the existing label set (spec sections 12 and 13): the triage set
(needs-triage, triage/accepted, triage/declined), the per-phase
labels (phase/assessment, phase/implementation, phase/backlog),
the verified and confirmed gates, and the phase B skip marker
(skip-implementation).

Scope note: the labels block is also reconciled with the repository's
live labels (the file has drifted: duplicate admin entries, three
colors lost to unquoted # in YAML, meta in the file but not live,
broken-link and techdocs-upstream live but not in the file). Live
labels win. The repository: section of the file is untouched.

Done when

The labels exist on cncf/techdocs (section 16, step 1). Expected apply
path: the Probot Settings app (verified alive in cncf/mentoring,
2026-06-25 sync; see the preflight issue) wakes on merge once the PR
fixes the file's unquoted # colors, and performs a full declarative
sync. This is why the file must be reconciled to live first: a real
sync deletes live labels missing from the file. If merge still applies
nothing, the labels are created by hand with gh label create (HC-4
permits by-hand bookkeeping). Either way, the path that happened is
recorded here.

Observations

Moved to the probe delegation's tracking issue (spec section 16, as
amended by 09a92bf). Branch naming, draft-PR reliability, token
scopes, Actions approval-wait, and review-comment access are
cloud-agent behaviors, and this step no longer delegates to the cloud
agent.

Spec references

Implements section 16, step 1, as amended by 09a92bf (components
drafted locally with Copilot CLI; the operator executes every GitHub
action); label set from sections 12 and 13; bound by P-1 (a human
reviews and merges; Copilot code review's findings are input, never
approval) and HC-4 (the change lands only through a reviewed PR).

[nate-double-u]

Merged as #367, and the Settings app performed a sync: live labels now exactly match settings.yml (36/36, verified via API). All nine assessment labels exist; admin picked up its description; meta was removed by the declarative sync as reconciled. Root cause (unquoted colors YAML-typed to null/int/float) confirmed by the fix applying. Fallback script not needed.