fix(ui): stat-tile overflow + visible build version

Two issues:

1. _StatTile in the Doctor page overflowed by ~6px on narrow
   widths because the Row containing the icon + label "AUDIT
   CHAIN" with letterSpacing=0.6 didn't fit in the ~90px
   constraint per tile (4 tiles in a Row sharing the page
   width). Fix: smaller icon (16→14), tighter gap, label wrapped
   in Flexible with TextOverflow.ellipsis, and the longest label
   shortened "AUDIT CHAIN" → "AUDIT" with the chain count moved
   to the subtitle.

2. The new redesign was easy to mistake for the previous build
   from the outside. Add a small monospaced version line right
   under "F∆I Studio" in the sidebar header:

       F∆I Studio
       v0.7.1 · warm-minimalism

   Self-identifying — "wrong build" is now visible without
   reading the about dialog.

Bumps fai_studio 0.7.0 -> 0.7.1.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/main.dart

@@ -16,6 +16,11 @@ import 'theme/theme.dart';
 import 'theme/tokens.dart';
 import 'widgets/widgets.dart';
 
+/// Studio's own build version. Bump on every UI commit so the
+/// running app self-identifies — visible in the sidebar header
+/// and quick-glance proof that you're seeing the current build.
+const String kStudioVersion = '0.7.1';
+
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
   // Restore the persisted endpoint and theme mode before the
@@ -218,7 +223,15 @@ class _Sidebar extends StatelessWidget {
               fontWeight: FontWeight.w600,
             ),
           ),
-          const SizedBox(height: FaiSpace.xs),
+          const SizedBox(height: 2),
+          Text(
+            'v$kStudioVersion · warm-minimalism',
+            style: FaiTheme.mono(
+              size: 10,
+              color: theme.colorScheme.primary,
+            ),
+          ),
+          const SizedBox(height: FaiSpace.md),
           // Connection pill.
           Padding(
             padding: const EdgeInsets.symmetric(horizontal: FaiSpace.lg),