FB-09: size default HUD widgets by title, not a fixed uniform cell

Adds minColSpanForLabel as a character-count proxy for how many grid
columns a metric's title needs, reworks HudWidgetLayout.defaultFor into
a left-to-right row-packing layout using it, enforces the same minimum
as a floor on manual resize, and splits _HudMetricValue's FittedBox so
the title renders at a fixed reference size while only the value
shrinks/grows to fill the remaining space.

Confirms a real, documented interaction with FB-08's _reflowRow: its
even column split has no awareness of a member's title-driven minimum
and can push one below it. Left unfixed per this ticket's own
Out-of-scope section -- _reflowRow's algorithm is FB-08's, not this
ticket's, to change.

Test count 426 -> 434, all green. flutter analyze unchanged (same 4
pre-existing, unrelated info-level issues).

lib/src/ui/components/draggable_resizable_hud_widget.dart

@@ -146,9 +146,18 @@ class _DraggableResizableHudWidgetState extends State<DraggableResizableHudWidge
                   });
                 },
                 onPanEnd: (_) {
+                  // FB-09: a rider can still make a widget larger than its title
+                  // needs (for a bigger value reading), but never smaller than the
+                  // title's own minimum -- clamped here rather than left to the
+                  // generic hudMinSpan floor in HudLayoutController.
                   final snappedColSpan =
-                      ((layout.colSpan * _cellWidth + _resizeDelta.width) / _cellWidth)
-                          .round();
+                      (((layout.colSpan * _cellWidth + _resizeDelta.width) /
+                              _cellWidth)
+                          .round())
+                          .clamp(
+                            minColSpanForLabel(layout.metric.label),
+                            hudMaxColSpan,
+                          );
                   final snappedRowSpan =
                       ((layout.rowSpan * _cellHeight + _resizeDelta.height) /
                               _cellHeight)

lib/src/ui/record/record_screen.dart

@@ -328,38 +328,41 @@ class _HudMetricValue extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final colors = Theme.of(context).colorScheme;
-    // FB-03: FittedBox owns sizing here -- structurally impossible to overflow, so
-    // maxLines/overflow are dropped from both Texts. fontSize: 10/18 below (still
-    // scaled by V3-05/FB-02's mounted-mode [scale]) are now just the "reference" size
-    // FittedBox scales down from at small widget sizes; the ratio between label and
-    // value size is preserved automatically as it scales. Note: BoxFit.scaleDown never
-    // enlarges past that reference size, so a widget resized to the grid's maximum
-    // span still shows the same reference text, just with more empty space around it
-    // -- not larger text filling the space.
-    return FittedBox(
-      fit: BoxFit.scaleDown,
-      child: Column(
-        mainAxisSize: MainAxisSize.min,
-        children: [
-          Text(
-            metric.label.toUpperCase(),
-            style: TextStyle(
-              fontSize: 10 * scale,
-              letterSpacing: 1,
-              color: colors.onSurfaceVariant,
+    // FB-09: the title is a plain, unwrapped Text at its fixed reference size -- it
+    // must always fit at a readable size, never shrinking along with the value. Only
+    // the value is wrapped in its own FittedBox, inside a Flexible so it claims
+    // whatever vertical space is left after the fixed-size title rather than both
+    // competing for space inside one shared FittedBox as before. maxLines/overflow are
+    // restored on the title as a safety net in case a future label is ever added that
+    // minColSpanForLabel's thresholds under-estimate.
+    return Column(
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        Text(
+          metric.label.toUpperCase(),
+          style: TextStyle(
+            fontSize: 10 * scale,
+            letterSpacing: 1,
+            color: colors.onSurfaceVariant,
+          ),
+          maxLines: 1,
+          overflow: TextOverflow.ellipsis,
+        ),
+        const SizedBox(height: 4),
+        Flexible(
+          child: FittedBox(
+            fit: BoxFit.scaleDown,
+            child: Text(
+              _value,
+              style: monoDigits.copyWith(
+                fontSize: 18 * scale,
+                fontWeight: FontWeight.bold,
+                color: _valueColor(colors),
+              ),
             ),
           ),
-          const SizedBox(height: 4),
-          Text(
-            _value,
-            style: monoDigits.copyWith(
-              fontSize: 18 * scale,
-              fontWeight: FontWeight.bold,
-              color: _valueColor(colors),
-            ),
-          ),
-        ],
-      ),
+        ),
+      ],
     );
   }
 }