Scale wet and dry calendar bars independently (#57)

In the calendar category strip, precip (Dry + rain intensity) and dry-streak
(Rain day + dry buckets) mix wet and dry categories. Heights scaled to the
single tallest bucket across both, so a dominant dry-day count flattened the
rain-intensity bars to ~2px and vice versa, hiding the opposing distribution.

Give each bucket a scale group (wet/dry) and size bars to the tallest bucket
within their own group. Temperature tiers share one group, so they scale
together as before.

static/calendar.js

@@ -534,20 +534,26 @@ function renderTotals(visible) {
       ["14+ dry", drynessColor(14), (d) => d >= 14],
     ];
     const vals = days.map((r) => r.dsr).filter((d) => d != null);
-    buckets = B.map(([label, color, fn]) => [label, color, vals.filter(fn).length]);
+    // Group (index 3) sets which categories share a height scale: the lone "Rain day"
+    // (wet) is scaled apart from the dry-streak buckets so it can't flatten them.
+    buckets = B.map(([label, color, fn], i) =>
+      [label, color, vals.filter(fn).length, i === 0 ? "wet" : "dry"]);
     title = "dry streak";
   } else if (metric === "precip") {
     const classes = days.map((r) => r.precip && r.precip.c).filter(Boolean);
-    buckets = [["Dry", drynessColor(7), classes.filter((c) => c === "dry").length]]
+    // Dry days scale independently of the rain-intensity buckets (wet) so a big dry
+    // count doesn't crush the rain bars — and vice versa.
+    buckets = [["Dry", drynessColor(7), classes.filter((c) => c === "dry").length, "dry"]]
       .concat(SCALE_RAIN.map((t) =>
-        [t.label, PRECIP_COLORS[t.c], classes.filter((c) => c === t.c).length]));
+        [t.label, PRECIP_COLORS[t.c], classes.filter((c) => c === t.c).length, "wet"]));
     title = "rain intensity";
   } else {
     const classes = days
       .map((r) => { const g = r[metric]; return g && g.c; })
       .filter(Boolean);
+    // Temperature tiers all share one scale group, so they scale together as before.
     buckets = SCALE_TEMP.map((t) =>
-      [t.label, TIER_COLORS[t.c], classes.filter((c) => c === t.c).length, t.c === "normal"]);
+      [t.label, TIER_COLORS[t.c], classes.filter((c) => c === t.c).length, "temp"]);
     title = (TEMP_METRIC_INFO[metric] || {}).label || "value";
   }
 
@@ -573,11 +579,15 @@ function renderTotals(visible) {
   // own color. Every category — including the neutral "Normal" center of the diverging
   // temperature scale — draws a line, so the strip reads as a full distribution.
   // Category names live in the color key below the grid too, so this stays terse.
-  // Line heights scale to the tallest category.
+  // Line heights scale to the tallest category *within each scale group* (index 3):
-  const maxLine = Math.max(1, ...buckets.map((b) => b[2]));
+  // for precip/dry-streak, wet and dry days scale independently, so a lopsided count
-  const LINE_MAX = 30;   // px — height of the most common category
+  // on one side doesn't shrink the opposing side's bars into invisibility. Temperature
-  const cols = buckets.map(([label, color, n]) => {
+  // tiers all sit in one group, so they still scale against each other as before.
-    const h = !n ? 0 : Math.max(2, Math.round(LINE_MAX * n / maxLine));
+  const maxByGroup = {};
+  for (const b of buckets) maxByGroup[b[3]] = Math.max(maxByGroup[b[3]] || 1, b[2]);
+  const LINE_MAX = 30;   // px — height of the tallest category in its group
+  const cols = buckets.map(([label, color, n, group]) => {
+    const h = !n ? 0 : Math.max(2, Math.round(LINE_MAX * n / maxByGroup[group]));
     const line = h ? `<span class="ct-line" style="height:${h}px"></span>` : "";
     // Caption stacks the category name over its value; the name reserves two lines
     // so the value figures stay aligned across columns whether a name wraps or not.