One-time: sync nightly.yml to main so the 06:00 UTC schedule stops failing

[erikdarlingdata]

Scheduled workflows execute the DEFAULT branch's copy of the workflow file. Main's stale nightly.yml still reads Dashboard/Dashboard.csproj (moved to deprecated/ by #1612), so the scheduled nightly build job fails every morning (first: run 30194606068, 2026-07-26). #1715 restructured dev's nightly.yml so the schedule only re-dispatches onto the dev ref - after ONE sync of the file to main, this trap class is dead permanently (main's copy will have exactly one tree-independent job) and nightly logic changes take effect the night they merge to dev.

The one manual step (admin, since check-pr-branch.yml blocks non-dev PRs to main by design):

git fetch origin && git checkout main && git pull origin main
git checkout origin/dev -- .github/workflows/nightly.yml
git commit -m "Sync nightly.yml from dev: scheduled runs execute main's copy of the workflow"
git push origin main

Alternative: let the next dev->main release promotion carry it, at the cost of a red scheduled nightly each morning until then. The dispatched path itself is already validated live (manual dispatch with -f from_schedule=true, run 30220289588). Full context in #1715.

🤖 Generated with Claude Code

[erikdarlingdata]

Decision recorded: this rides the next dev->main release promotion (the merge carries nightly.yml automatically - no action needed at release time). Until then the 06:00 UTC scheduled run stays red each morning; tonight's artifacts were produced via manual dispatch (run 30220289588), and the same one-liner works any day artifacts are needed early: gh workflow run nightly.yml --ref dev -f from_schedule=true. Keep this issue open until the first post-release scheduled nightly goes green, then close it as verified.

[erikdarlingdata]

The pending dev-to-main release cut carries the current nightly.yml to main, which is exactly the sync this issue asks for. Closing when the release lands rather than doing a one-off file sync now; if the release slips meaningfully, a direct sync PR remains the fallback.

[erikdarlingdata]

Closing per the decision already recorded here: the sync needs no action of its own - the next dev-to-main release promotion carries the current nightly.yml automatically (#1807's CI-pin changes ride the same merge). Until the cut lands, the 06:00 UTC scheduled run stays red each morning, expected; the manual dispatch one-liner above works any day artifacts are needed early. Nothing is lost by closing the reminder.