Dashboard: flag non-main branches and print follow-up commands

[Jammy2211]

Extend scripts/pyauto_status.sh so the dashboard turns from a passive readout into an actionable cleanup checklist:

1. b flag for non-main / non-tracked branches. The BRANCH column shows the name, but main and fix/some-feature look identical at a glance — a forgotten feature branch on a canonical checkout (e.g. euclid_strong_lens_modeling_pipeline has been on fix/extra-galaxies-gui-vis-index for weeks) should pop out. Heuristic: flag with b when current branch != upstream branch component (or upstream=NONE and branch != main).

2. Follow-up commands section at the bottom, grouped by category:

   • Pull (clean, behind, not ahead) — copy-pasteable git -C <abs-path> pull --ff-only per repo.
   • Set missing upstream (branch=main, upstream=NONE) — git -C <abs-path> branch --set-upstream-to=origin/main main.
   • Investigate manually — one-line note (no command) for diverged / behind+dirty / unexpected-branch cases.

Section is suppressed entirely when there's nothing to suggest, so the clean case stays quiet.

Replaces the need for a separate pyauto-pull shell function — the printed commands ARE the action. Boring case automated, judgment cases surfaced.

Refs: autoprompt 05 (re-scoped — full /sync skill spec deemed over-engineered now that prompt 03 forbids the catastrophic reset pattern).

[Jammy2211]

Shipped via #10 (squash-merged ea72d8e). Dashboard now flags non-main branches with b and prints copy-pasteable follow-up commands grouped by Pull / Set missing upstream / Investigate manually. Replaces the rejected heavyweight /sync skill spec from autoprompt 05 — printed commands are the action.