probe: assert a 7-char pattern name renders un-ellipsised in a song cell nf-l8ew ← Beads

Twinned from https://github.com/cfsh/ninefold/issues/345 by tools/beads/import_github.py's reconcile pass.

Deferred from PR #338's review (gate item, flagged twice): FitPennantText's character budget is pure arithmetic but can only be tested with Godot's font metrics, so it needs a probe — and the probe needs a deterministic 7-char pattern name in the seeded demo (current max is 5 chars, e.g. BREAK/SPARK). Shape: add/rename a demo pattern to a 7-char pool name (e.g. harmony), then a probe leg asserting its song-cell pennant renders the full name (no …) — e.g. an expect step reading the trimmed text, or a pixel assertion at the cell's right edge.

Refs #338.