S allius/issue395 (#399)

* add button for languages setting

* build a web module for the dashboard

- load all python module from local dir
- initialize Blueprint and Babel

* set a default key for secure cookies

* add translations to docker container

* improve translation build  

- clean target erases the *.pot
- don't modify the resurt of url_for() calls
- don't translate the language description

* translate connection table, fix icon

* build relative urls for HA ingress

* fix unit test, increase coverage

app/translations/de/LC_MESSAGES/messages.po

@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: tsun-gen3-proxy 0.14.0\n"
 "Report-Msgid-Bugs-To: EMAIL@ADDRESS\n"
-"POT-Creation-Date: 2025-04-20 21:21+0200\n"
+"POT-Creation-Date: 2025-04-28 21:00+0200\n"
 "PO-Revision-Date: 2025-04-18 16:24+0200\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language: de\n"
@@ -19,11 +19,31 @@ msgstr ""
 "Content-Transfer-Encoding: 8bit\n"
 "Generated-By: Babel 2.17.0\n"
 
-#: src/web/templates/base.html.j2:27
+#: src/web/conn_table.py:57
+msgid "Device-IP:Port"
+msgstr "Geräte-IP:Port"
+
+#: src/web/conn_table.py:57
+msgid "Device-IP"
+msgstr "Geräte-IP"
+
+#: src/web/conn_table.py:58
+msgid "Serial-No"
+msgstr "Seriennummer"
+
+#: src/web/conn_table.py:59
+msgid "Cloud-IP:Port"
+msgstr "Cloud-IP:Port"
+
+#: src/web/conn_table.py:59
+msgid "Cloud-IP"
+msgstr "Cloud-IP"
+
+#: src/web/templates/base.html.j2:37
 msgid "Updated:"
 msgstr "Aktualisiert:"
 
-#: src/web/templates/base.html.j2:46
+#: src/web/templates/base.html.j2:58
 msgid "Connections"
 msgstr "Verbindungen"