feat(train): a ride's distance from the wheel where GPS falls short (ADR 0030, D49)

The speed sensor's wheel gives a ride's distance, splits, progress and live
speed where GPS made less than 90 % of its way (a turbo trainer, a tunnel);
its circumference starts at 2105 mm, is learnt from rides with 2 km of GPS
or typed on the Record sheet.

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

@@ -680,5 +680,14 @@
   "workoutAverageCadence": "average cadence",
   "workoutNormalisedPower": "normalised power",
   "workoutRpmValue": "{rpm} rpm",
-  "@workoutRpmValue": {"placeholders": {"rpm": {"type": "int"}}}
+  "@workoutRpmValue": {"placeholders": {"rpm": {"type": "int"}}},
+  "recordWheel": "Wheel circumference",
+  "recordWheelMeasured": "{mm} mm, measured by GPS",
+  "@recordWheelMeasured": {"placeholders": {"mm": {"type": "int"}}},
+  "recordWheelTyped": "{mm} mm, as you typed it",
+  "@recordWheelTyped": {"placeholders": {"mm": {"type": "int"}}},
+  "recordWheelDefault": "{mm} mm until GPS has measured it on a ride of 2 km",
+  "@recordWheelDefault": {"placeholders": {"mm": {"type": "int"}}},
+  "recordWheelHint": "In millimetres, as the tyre says (700×25C: 2105); empty to have GPS measure it",
+  "recordWheelSave": "Save"
 }