feat(train): a workout's sheet pulled up squares off, its bar naming the activity

As Strava's: over the last 6 % below the highest the sheet goes, its
top corners square off from 28 to 0 and its handle folds away, so the
bar above, opaque by then, meets it without the map showing through
the corners. The bar names the activity rather than the workout, whose
name already heads the sheet: it was in sight twice. sheetSquared in
track_camera.dart, tested beside barShown. ADR 0030, D65.

Whats-New: A workout's page pulled all the way up meets the bar square, which names the activity.
Whats-New-De: Ganz hochgezogen schließt die Seite eines Trainings eckig an die Leiste an, die die Sportart nennt.

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

docs/adr/0030-halkyon-train.md

@@ -1719,6 +1719,12 @@ Strava. What was found, 27 Oct:
     has a row of its own now, as wide as the list, each label on one line and scaled
     down where it still doesn't fit (larger text), rather than shortened labels or a
     menu, which would hide the choice behind a tap.
+  - **A workout's sheet pulled all the way up, as Strava's**: over the last 6 % of the
+    page below the highest it goes, its top corners square off (28 to 0) and its
+    handle folds away, so that the bar above it, opaque by then, meets it without the
+    map showing in the corners. The bar names the activity (Running), not the
+    workout, whose name is the sheet's first line: once in sight, not twice (D63 had
+    the bar take the sheet's title).
 ## Consequences
 
 - Train's sensors are one pattern: open profiles read by the app itself, on the phone;