fix(snap): the Store takes the snap: no mail addresses among its links

The Store refused v0.16.0's upload with "Links must be http(s):// URLs":
contact and issues held support@halkyon.app, which snapcraft's reference
allows but the Store doesn't. Both go; the address moves into the
description, where the Store page shows it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

snap/snapcraft.yaml

@@ -20,13 +20,17 @@ description: |
 
   It starts with an anonymous account; signing in with GitHub later keeps
   everything. It connects to learn.halkyon.eu, the project's instance.
+
+  Questions and reports: support@halkyon.app
 license: AGPL-3.0-or-later
 source-code: https://code.halkyon.app/project-halkyon/halkyon_learn
 # The project's, not an instance's: the app works with any instance.
 website: https://halkyon.app/learn
-contact: support@halkyon.app
-# Reports by mail until people can open an account on the issue tracker.
-issues: support@halkyon.app
+# No contact or issues: the Store refuses an upload whose links aren't http(s) URLs
+# ("Links must be http(s):// URLs", checked with snapcraft v9.1.4 on 2026-10-14),
+# though snapcraft's reference allows mail addresses there (canonical/snapcraft#6062
+# asks for them). Reports come by mail until people can open an account on the issue
+# tracker, so the address is in the description.
 # The app's icon with rounded corners, made by tool/app_icons.py; also the desktop file's.
 icon: snap/gui/halkyon-learn.png
 grade: stable