overhaul ClideMarkdown renderer

Inline grouping collapses consecutive inline nodes (strong, em, code,
a, del) into a single RichText widget instead of rendering each as a
separate block — fixes tight list items like `builtin.git` appearing
on its own line.  HTML entity unescaping moved from pre-parse (useless)
to post-AST extraction where the markdown package actually introduces
the entities.  Explicit Josefin Sans Light font family and 1.25 line
height on all RichText spans.  Body text bumped to 16px; inline code
uses clideFontMono for visual weight parity.

Adds onRecordTap callback — markdown links matching [DQRT]-\d+ render
as tappable WidgetSpans with hover underline.  New typography constants
clideFontSmall (12), clideFontBadge (11), clideLineHeight (1.25).

Co-Authored-By: Claude <noreply@anthropic.com>

lib/widgets/src/typography.dart

@@ -56,6 +56,9 @@ const String clideMonoFamily = 'JetBrainsMono';
 const double clideFontBody = 15;
 const double clideFontCaption = 14;
 const double clideFontMono = 14;
+const double clideFontSmall = 12;
+const double clideFontBadge = 11;
+const double clideLineHeight = 1.25;
 
 /// System fallback chain. Ordered by platform prevalence + quality of
 /// programming-ligature / box-drawing coverage.