Home: spread the activity table's slack, shorten its counts, shorten the fade

The trend column carried `w-full`, which made it swallow every spare pixel:
the five columns beside it huddled in the left 40% with a dead gap before the
curve. It takes a bounded third now, so the auto layout spreads the rest over
the columns that have content to show, and a long flow name still widens its
own column into the card's scroll.

`si` reaches the rollup counts it was written for — 179240 executions reads as
"179k", and the failure badge and the failures tile follow. The plain window
leaves the small ones alone: 615 is still 615. The standing counts (nodes,
flows running, queue depth) stay exact, as does everything acted on digit by
digit.

The fade ran a full 40 of the 100-unit box. In a table cell three times the
width of a panel that washed out readings still worth seeing, so it is 25 —
a hint at the left end rather than a quarter of the series.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XC2jX6Hdj7pxGGKzBTrbqB

frontend/src/lib/utils.ts

@@ -24,9 +24,11 @@ const SI_STEPS: [number, string][] = [
  * keeps a reading in its column, and beyond giga or micro the exponent is.
  *
  * Where it applies: anything read at a glance and bounded by the width of a
- * tile, a table cell, an axis gutter or a legend. Exact counts (executions,
- * failures) and anything the user is about to act on — a payload, a form
- * field, the edge inspector's value — stay unrounded.
+ * tile, a table cell, an axis gutter or a legend — a rollup's own counts
+ * included, since 179240 executions is a size, not a number anyone reads
+ * digit by digit. What the user acts on stays unrounded: a payload, a form
+ * field, the edge inspector's value, and the standing counts (nodes, flows
+ * running, queue depth) that are small by nature and exact by meaning.
  */
 export function si(value: number, digits = 3): string {
   if (!Number.isFinite(value)) return "--"