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>

CHANGELOG.md

@@ -8,6 +8,9 @@ All notable changes to Housecarl are documented here. The format follows
 
 ### Added
 
+- **Quota usage as a share.** What a quota used shows its percentage
+  (`12.3 GB of 50.0 GB used (24%)`, each address's in the quota
+  dialog), on the Rules page, the dashboard and in `hc quotas`.
 - **Reset one address's quota, or give some back.** `hc rule
   reset-quota ID --address ADDR` starts only that device's allowance
   again; `--give 5gbytes` takes that much off what was used instead (one
@@ -93,6 +96,10 @@ All notable changes to Housecarl are documented here. The format follows
   the old entries behind. Now a total starts at the addresses' sum,
   wider groups add up their addresses, and what can't be carried starts
   again with a warning (`quota_restarts`) on the change.
+- Statistics' Quotas card linked every entry to the Rules page, not to
+  its rule; each now opens its rule, named. Per-address quotas were
+  missing from it (and from the `quota:rN` series): they count their
+  addresses' sum.
 - `hc stats top devices` listed each device twice (once for what it
   received, once for what it sent); it is one row with both again.
 - `hc rule add --before/--after/--first` made two changes (create at the