chore(deps): bump actions/setup-node from 4 to 7

[nateshpp]

What this PR does

Recreates Dependabot's #137 with the repo's snapshot regenerated, since Dependabot's own PR fails this repo's check:snapshot gate (it has no way to know this repo requires .modonome/snapshot/* regenerated alongside any tracked-file change). Same version bump, same diff across all 9 files; Dependabot's #137 will be closed as superseded.

• actions/setup-node bumped to 7 across action.yml, ci.yml, modonome-auto.yml, modonome-review.yml, modonome-schedule.yml, publish-edge.yml, publish.yml, self-govern.yml, sync-site-data.yml (tag-pinned references move to v7; SHA-pinned references move to the v7.0.0 commit SHA, matching Dependabot's own resolution).
• .modonome/snapshot/* regenerated to match.
• Follow-up fix: scripts/agent/triggers.mjs, the generator for modonome-schedule.yml, had the setup-node SHA hardcoded in two places (a constant and a separate template comment); only the constant was in sync before this PR's second commit, which fixes both so the generator's output matches what is committed.

Governance checklist

• npm run verify gates relevant to this diff pass locally (style, repo hygiene, snapshot freshness, attestation freshness, self-application conformance, gate DAG)
• No em dashes in any tracked file
• No AI co-author lines in commit messages
• If ratchet logic changed: N/A, no ratchet files touched (only the Node setup step's action version)
• If a new AgentProof scenario: N/A
• If config schema changed: N/A
• If prompt changed: N/A

Test evidence

node scripts/snapshot.mjs . --check
Snapshot is current.

npm run check:attestation
PASS: .modonome/policy-attestation.json is current.

node scripts/check-style.mjs .
Style check passed (185 advisory warning(s), grandfathered term(s) not yet migrated).

node scripts/check-repo-hygiene.mjs
Repo hygiene check passed. No loose ends detected.

node scripts/check-self-application.mjs
PASS: every repo-local self-governance invariant holds.

node scripts/check-gate-dag.mjs
Gate graph valid.

npm test
# tests 914
# pass 914
# fail 0