bump phosphor icon font to size 1.0, fix welcome tests

Phosphor glyph fontSize set to 1.0 in unit space so glyphs fill
the full icon size (16px in the rail). Welcome tests updated to
match the redesigned view.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/lib/widgets/src/clide_icon_rail.dart

@@ -106,7 +106,7 @@ class _RailButton extends StatelessWidget {
                   ),
                 ),
               ),
-              child: ClideIcon(item.icon, size: 14, color: color),
+              child: ClideIcon(item.icon, size: 16, color: color),
             ),
           ),
         ),

app/lib/widgets/src/icons/phosphor.dart

@@ -11,7 +11,7 @@ class PhosphorIconPainter extends ClideIconPainter {
   @override
   void paint(ui.Canvas canvas, ui.Color color) {
     final builder = ui.ParagraphBuilder(
-      ui.ParagraphStyle(fontFamily: family, fontSize: 0.75, height: 1.0, textAlign: ui.TextAlign.center),
+      ui.ParagraphStyle(fontFamily: family, fontSize: 1.0, height: 1.0, textAlign: ui.TextAlign.center),
     )
       ..pushStyle(ui.TextStyle(color: color, fontFamily: family))
       ..addText(String.fromCharCode(codePoint));