A buttons widget: a grid of presses on one message

Several stateless instructions where a single button is one — six presets are
otherwise six tiles to place, six titles to read, and the message they share
repeated six times. Nothing is read back, as for a single button: what these
send is an instruction, and the last one sent is not a state to draw.

Auto-fit columns rather than a configured count: a tile is resized in the
editor and scaled again to whatever panel it hangs on, so how many fit is not
something the document can know.

The editor reads `cfg.buttons` raw rather than through `buttonsOf`, which
drops the blanks — a row being typed into is blank until the first keystroke.

Also carried along by the hooks: the generated SDK was stale (it had no
`RunsReadMetricNames`) and one pre-existing block in `test_panels.py` was
unformatted.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bm2HwnRsTDpeWjSPNJxQd

frontend/src/components/Dashboard/ui/core/config.ts

@@ -89,6 +89,15 @@ export function asOriginal(
   return match ? match.value : selected
 }
 
+/** One press a button grid draws, as the document stores it. */
+export type ButtonEntry = { label?: string; value?: unknown }
+
+/** The presses a grid draws. A row with neither half is not one. */
+export const buttonsOf = (widget: WidgetDef): ButtonEntry[] =>
+  ((config(widget).buttons ?? []) as ButtonEntry[]).filter(
+    (entry) => entry.label || entry.value !== undefined,
+  )
+
 /**
  * How many readings one bar draws, and a hard ceiling.
  *