New reverse zone: pick from the networks your records use, sized around them

The Zones page's New reverse zone lists every network the records use without a reverse zone, in every view, also where nothing is suggested (suggestions off, dismissed, public views), marked. Picking one fills in the network and view; size buttons (/48 /56 /64 /128, /16 /24 /32) re-mask it around a record's address, so a /48 becomes the records' own /64. Fill stays on. jarl zone suggest-reverse --all [--view V]; GET /reverse-zones/suggestions?all=1&view=.

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

CHANGELOG.md

@@ -37,6 +37,11 @@ All notable changes to Jarl are documented here. The format follows
   delegation and its glue stay.
 - Zone commands take a network for a reverse zone: `jarl zone show
   10.0.10.0/24`.
+- **New reverse zone** (Zones page) lists the networks your records use
+  without a reverse zone, in every view, also where nothing is suggested
+  (suggestions off, dismissed, public views); pick one, change its size
+  (/48, /56, /64, /128 for IPv6, around the records' address) and create
+  it filled. `jarl zone suggest-reverse --all [--view V]`.
 - Comparing one name across views: `jarl zone diff adbraun.lol nas [A]`,
   and a **Compare** button on each record.