Seconds per clock, and type that scales with the bar height

Seconds move from one bar-wide switch to a per-clock setting. A clock's own
`showSeconds` wins, the top-level one is the default for clocks with no
opinion, and the centre clock gets `local.showSeconds` since it has no entry in
`clocks[]`. An explicit false on a clock beats a true default, so the check is
for the property's presence rather than its truthiness.

The tick rate follows what is actually displayed: `anyShowsSeconds()` decides
between a per-second and a per-minute SystemClock, so a bar showing no seconds
does not wake the shell sixty times as often to redraw an identical minute.

`barSize` is now editable from the popup, and everything drawn on the bar is
sized against the theme's own bar height rather than pinned to the theme's
12px type. A taller bar carries proportionally larger text, gaps and rule; at
the theme's own height the scale is exactly 1, so nothing moves. Heights are
clamped to 12-120 rather than rejected, so a value the editor can produce can
never be one the config layer silently discards.

Fixes a latent bug this surfaced: updateRow() rebuilt a draft row from a fixed
pair of fields, so editing a clock's label would have thrown away its own
seconds setting. It now copies every key the row had.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MhxtL7WzL5XmuTd8GHbcTY

ClockModel.js

@@ -84,6 +84,29 @@ function isWorkingHours(wall, hours) {
   return hour >= start || hour < end
 }
 
+// Seconds are decided per clock, falling back to the config-wide default.
+// An explicit `false` on a clock has to beat a `true` default, so the check is
+// for the property's presence, not its truthiness.
+function showsSeconds(entry, fallback) {
+  if (entry && typeof entry.showSeconds === "boolean") return entry.showSeconds
+  return fallback === true
+}
+
+// Whether anything on the bar is showing seconds, which is what decides
+// between a per-second and a per-minute tick. Ticking every second when
+// nothing displays them wakes the whole shell sixty times as often for no
+// visible change.
+function anyShowsSeconds(config) {
+  var cfg = config || {}
+  var fallback = cfg.showSeconds === true
+  if (showsSeconds(cfg.local, fallback)) return true
+  var entries = Array.isArray(cfg.clocks) ? cfg.clocks : []
+  for (var i = 0; i < entries.length; i++) {
+    if (showsSeconds(entries[i], fallback)) return true
+  }
+  return false
+}
+
 function isValidLabel(label) {
   return typeof label === "string" && label.replace(/^\s+|\s+$/g, "").length > 0
 }
@@ -93,6 +116,7 @@ function isValidLabel(label) {
 // show the label struck through instead of quietly lying about the time.
 function buildClock(entry, offsets, utcMs, localOffset, options) {
   var opts = options || {}
+  var withSeconds = showsSeconds(entry, opts.showSeconds)
   var timezone = String(entry && entry.timezone ? entry.timezone : "")
   var label = isValidLabel(entry && entry.label) ? String(entry.label).replace(/^\s+|\s+$/g, "") : timezone
   var offset = parseOffset(offsets ? offsets[timezone] : null)
@@ -100,7 +124,8 @@ function buildClock(entry, offsets, utcMs, localOffset, options) {
   if (offset === null) {
     return {
       label: label, timezone: timezone, known: false,
-      time: "--:--", marker: "", delta: 0, relativeMinutes: 0, working: false
+      time: withSeconds ? "--:--:--" : "--:--",
+      marker: "", delta: 0, relativeMinutes: 0, working: false
     }
   }
 
@@ -112,7 +137,7 @@ function buildClock(entry, offsets, utcMs, localOffset, options) {
     label: label,
     timezone: timezone,
     known: true,
-    time: formatTime(wall, opts.showSeconds === true),
+    time: formatTime(wall, withSeconds),
     marker: dayMarker(delta),
     delta: delta,
     relativeMinutes: offset - localOffset,
@@ -165,7 +190,7 @@ function buildBar(config, offsets, utcMs, localOffsetRaw) {
     // of the trailing group where they are visible but never mis-ordered.
     right: right.concat(unknown),
     center: {
-      time: formatTime(localWall, options.showSeconds),
+      time: formatTime(localWall, showsSeconds(cfg.local, options.showSeconds)),
       date: localWall.getUTCFullYear() + "-" + pad2(localWall.getUTCMonth() + 1) + "-" + pad2(localWall.getUTCDate()),
       offsetMinutes: localOffset
     }
@@ -211,6 +236,8 @@ if (typeof module !== "undefined" && module.exports) {
     dayDelta: dayDelta,
     dayMarker: dayMarker,
     isWorkingHours: isWorkingHours,
+    showsSeconds: showsSeconds,
+    anyShowsSeconds: anyShowsSeconds,
     buildClock: buildClock,
     buildBar: buildBar,
     zonesToProbe: zonesToProbe,