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/components/Common/Sparkline.tsx

@@ -9,8 +9,14 @@ const PAD = 8
 /** Above this ratio a linear series is all baseline and one spike. */
 const LOG_RATIO = 100
 
-/** How far the left end fades over, in viewBox units. */
-const FADE = 40
+/**
+ * How far the left end fades over, in viewBox units — a quarter of the width.
+ *
+ * Proportional, so it reads the same in a panel and in a table cell three
+ * times as wide. Any more and a wide curve loses readings that are still
+ * part of what the series says.
+ */
+const FADE = 25
 
 /** Enough digits to tell two neighbouring readings apart. */
 const READOUT_DIGITS = 4