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/pages/doctor.dart

@@ -142,10 +142,10 @@ class _SummaryStrip extends StatelessWidget {
         ),
         const SizedBox(width: FaiSpace.md),
         _StatTile(
-          label: 'Audit chain',
+          label: 'Audit',
           value: snapshot.chainHealthy ? '✓' : '⚠',
           subtitle:
-              '${snapshot.eventChainVerified}/${snapshot.eventChainTotal} verified',
+              '${snapshot.eventChainVerified}/${snapshot.eventChainTotal} chain',
           icon: Icons.shield_outlined,
           tone: snapshot.chainHealthy
               ? FaiPillTone.success
@@ -196,14 +196,17 @@ class _StatTile extends StatelessWidget {
           children: [
             Row(
               children: [
-                Icon(icon, size: 16, color: theme.colorScheme.onSurfaceVariant),
-                const SizedBox(width: FaiSpace.sm),
-                Text(
-                  label.toUpperCase(),
-                  style: theme.textTheme.labelSmall?.copyWith(
-                    color: theme.colorScheme.onSurfaceVariant,
-                    letterSpacing: 0.6,
-                    fontSize: 10,
+                Icon(icon, size: 14, color: theme.colorScheme.onSurfaceVariant),
+                const SizedBox(width: FaiSpace.xs),
+                Flexible(
+                  child: Text(
+                    label.toUpperCase(),
+                    overflow: TextOverflow.ellipsis,
+                    style: theme.textTheme.labelSmall?.copyWith(
+                      color: theme.colorScheme.onSurfaceVariant,
+                      letterSpacing: 0.5,
+                      fontSize: 10,
+                    ),
                   ),
                 ),
               ],