fix(release): add missing confirm-modal + staged-banner lang keys

The shipped Release UI references release.confirm_title, confirm_body,
confirm_action and staged_label, but neither lang/de/release.php nor
lang/en/release.php defined them, so the R5 confirm modal and the staged
success banner leaked raw keys (R9/R17). Add the four keys to both locales.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lang/de/release.php

@@ -11,6 +11,10 @@ return [
     'bump_minor' => 'Minor-Beta (:v)',
     'bump_major' => 'Major-Beta (:v)',
     'hint' => 'Schneidet einen Beta-Tag und pusht ihn nach Gitea → Mirror → CI → Staging.',
+    'confirm_title' => 'Beta schneiden?',
+    'confirm_body' => 'Beta :target wird geschnitten und nach Gitea → Mirror → CI → Staging gepusht. Das stößt einen Deploy auf der Staging-Instanz an.',
+    'confirm_action' => 'Schneiden & pushen',
+    'staged_label' => 'Zuletzt geschnitten:',
     'running' => 'Beta :target wird geschnitten und gepusht …',
     'staged' => 'Beta :tag gepusht → Mirror → CI → Staging.',
     'failed' => 'Release fehlgeschlagen: :reason',

lang/en/release.php

@@ -11,6 +11,10 @@ return [
     'bump_minor' => 'Minor beta (:v)',
     'bump_major' => 'Major beta (:v)',
     'hint' => 'Cuts a beta tag and pushes it to Gitea → mirror → CI → staging.',
+    'confirm_title' => 'Cut beta?',
+    'confirm_body' => 'Beta :target will be cut and pushed to Gitea → mirror → CI → staging. This triggers a deploy on the staging instance.',
+    'confirm_action' => 'Cut & push',
+    'staged_label' => 'Last cut:',
     'running' => 'Cutting and pushing beta :target …',
     'staged' => 'Beta :tag pushed → mirror → CI → staging.',
     'failed' => 'Release failed: :reason',