feat(train): Settings over the tabs from a cog on Home and Profile, the account near its foot (ADR 0030, D60)

As Learn's: a cog atop Home and Profile, with the count of accounts
waiting for whoever operates the instance, opens Settings over the tabs,
where an account sheet had held the account and the training's screens.
Grouped in cards: the operator's card, the training (your body, Health
Connect, the Polar Loop, music, those the device has), the account near
the foot, About Halkyon Train last, and the version small at the very
bottom.

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

apps/train/halkyon_train_flutter/lib/l10n/app_de.arb

@@ -12,7 +12,7 @@
   "accountTitle": "Konto",
   "accountDeleteMessage": "Dein Konto wird auf dem Server und auf all deinen Geräten gelöscht. Dies kann nicht rückgängig gemacht werden.",
 
-  "aboutTitle": "Über",
+  "aboutTitle": "Über Halkyon Train",
 
   "homeRecordHint": "Zeichne eins mit dem Knopf unten auf.",
   "recordAction": "Aufzeichnen",
@@ -563,5 +563,8 @@
   "shellTabGroups": "Gruppen",
   "shellTabProfile": "Profil",
   "groupsLaterTitle": "Gruppen kommen später",
-  "groupsLaterHint": "Mit anderen trainieren, in euren eigenen Gruppen, kommt in einer späteren Version von Train."
+  "groupsLaterHint": "Mit anderen trainieren, in euren eigenen Gruppen, kommt in einer späteren Version von Train.",
+  "settingsTitle": "Einstellungen",
+  "settingsTraining": "Training",
+  "settingsVersion": "Version {version} (Build {build})"
 }