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_en.arb

@@ -14,7 +14,7 @@
   "accountTitle": "Account",
   "accountDeleteMessage": "Your account is deleted on the server and on all your devices. This can't be undone.",
 
-  "aboutTitle": "About",
+  "aboutTitle": "About Halkyon Train",
 
   "homeRecordHint": "Record one with the button below.",
   "recordAction": "Record",
@@ -710,5 +710,9 @@
   "shellTabGroups": "Groups",
   "shellTabProfile": "Profile",
   "groupsLaterTitle": "Groups come later",
-  "groupsLaterHint": "Training with others, in groups of your own, comes in a later version of Train."
+  "groupsLaterHint": "Training with others, in groups of your own, comes in a later version of Train.",
+  "settingsTitle": "Settings",
+  "settingsTraining": "Training",
+  "settingsVersion": "Version {version} (build {build})",
+  "@settingsVersion": {"placeholders": {"version": {"type": "String"}, "build": {"type": "String"}}}
 }