Act on a run, and read Home top-down

Runs: a run can now be deleted (DELETE /runs/{id}, cancelling a live one
first), exported as csv from the screen's own filters, and its flow label
opens the flow. Its "Parameters" panel became "Inputs" and lists every
input the flow declares, marking the ones that took the flow's own value
rather than the run's — the comparison table resolves the same defaults
instead of printing "unset".

Home reads brain, dashboards, health, flows: the mosaic is one full-width
scrolling strip, and the flows list and the flow-activity rollups merged
into a single left-joined table so a flow's state and its numbers sit on
one row.

Charts take a drag to narrow the x window and a double click or tap to
come back out. UplotChart holds the scale and passes resetScales:false
while a window is held, which is what the old comment said made this
impossible.

frontend/scripts/capture-screenshots.mjs

@@ -81,7 +81,7 @@ for (const theme of ["light", "dark"]) {
     // Home's sections fetch independently, so networkidle can fall between them
     // and photograph the skeletons. The flow table is the last of them to land.
     await page
-      .getByText(/Flow activity/i)
+      .getByText(/activity over the last/i)
       .first()
       .waitFor({ timeout: 15000 })
     await page.waitForTimeout(1500)