Compare views: start with a view the zone is linked to

The tab picked the first other view in view order, so a zone linked with
one view opened compared with an unrelated one.

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

CHANGELOG.md

@@ -12,6 +12,11 @@ All notable changes to Jarl are documented here. The format follows
   jarld` works too. The alias is linked when the unit is enabled; the
   package relinks a unit enabled by an older version on upgrade.
 
+### Changed
+
+- A linked zone's Compare views tab starts with a view it is linked to,
+  not the first other view.
+
 ## [0.6.0] - 2026-10-13
 
 ### Added