feat(ui): tabs folding into the title, in Learn's and Train's Profile (ADR 0030, D60)

halkyon_ui's FoldingTabs: the tab row under the app bar's title at the
top, scrolling away with the content, the chosen tab's name then small
under the title, which, tapped, scrolls back up to the row, as Strava's.
Learn's Profile (Profile, Statistics) is built on it, and Train's
Profile in tabs: Progress (your body, the last 12 weeks, this year),
Days, and Plans where the device doesn't record.

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

@@ -1528,6 +1528,13 @@ Strava. What was found, 27 Oct:
   in Profile's tab), shown while the band gave figures for today, and so for someone
   with a Loop alone; above the week, which waits for the first workout, and above
   Home's message while there is none.
+  Profile's tabs fold into the title as Strava's (halkyon_ui's `FoldingTabs`, Learn's
+  Profile on it too): Progress (the cards above), Days, and Plans where the device
+  doesn't record; at the top the tab row shows under the title, scrolled down it
+  scrolls away with the content and the chosen tab's name shows small under the
+  title, which, tapped, scrolls back up to the row. The row alone is the scroll view's
+  header, nothing pinned, so the tabs' lists need no room kept for it and stay plain
+  `ListView`s.
 
 ## Consequences