fix theme picker integration test; one bake for build-time facts (T-116)

The test was awaiting services.commands.execute('theme.pick') whose
Future doesn't complete until the dialog is dismissed — deadlock.
Fire-and-forget around pumpAndSettle, then tap Cancel, then await
the original future. Also tear the widget tree down before
services.dispose() so listening widgets unsubscribe first.

Pre-existing layout overflow in the welcome _StatusLine surfaced
when running the test at narrower viewports. Switched to a whole-
row FittedBox(scaleDown) — uniform shrink on narrow screens, no-op
at standard widths.

User flagged the hardcoded 'clide 2.0.0-dev' string. Replaced with
one generated lib/src/build_info.g.dart (gitignored, regenerated
by `make gen-build-info` from pubspec.yaml + git short SHA + UTC
clock). The same target re-syncs assets/licenses.yaml self.version
in place — no second source. Every make build/run/test depends on
it implicitly. Welcome status line now reads `clideVersion`. Stale
fontSize literals in welcome_view swept to typography constants;
clideFontMeta=13, clideFontDialogTitle=16, clideFontWelcomeBanner=52
added to fill gaps in the scale.

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

lib/widgets/src/typography.dart

@@ -56,8 +56,14 @@ const String clideMonoFamily = 'JetBrainsMono';
 const double clideFontBody = 15;
 const double clideFontCaption = 14;
 const double clideFontMono = 14;
+const double clideFontMeta = 13;
 const double clideFontSmall = 12;
 const double clideFontBadge = 11;
+// Larger semantic sizes that aren't body text. clideFontDialogTitle is
+// the modal/dialog heading; clideFontWelcomeBanner is the oversized
+// "clide" mark on the welcome screen — one-off but worth naming.
+const double clideFontDialogTitle = 16;
+const double clideFontWelcomeBanner = 52;
 const double clideLineHeight = 1.25;
 
 /// System fallback chain. Ordered by platform prevalence + quality of