Quotas: usage as a share, and their statistics per rule

What a quota used shows its percentage of the allowance on the Rules
page (line and dialog), the dashboard and in hc quotas. Statistics'
Quotas card links each entry to its rule, named, without the share of
the total; per-address quotas are in it at last: their quota:rN series
is the sum of their addresses.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/stats/collector.go

@@ -402,7 +402,10 @@ func (c *Collector) sample(ctx context.Context, minute int64) map[string]int64 {
 			for set, es := range t.QuotaSets {
 				kind := strings.TrimSuffix(strings.TrimSuffix(set, "_v4"), "_v6")
 				for _, e := range es {
-					addTop(kind, e.Addr, c.table.of(set+"/"+e.Addr, e.Used))
+					d := c.table.of(set+"/"+e.Addr, e.Used)
+					addTop(kind, e.Addr, d)
+					// A per-address quota's series is its addresses' sum.
+					add("quota:"+strings.TrimPrefix(kind, "quota_"), d)
 				}
 			}
 			for set, es := range t.DeviceSets {