test sweep: icons, log.trace, DialogHost, FilesDropped getters (T-91)

Three small additions to push coverage toward the 90% target:

- test/widgets/icons_test.dart: one sweep test calling .paint() on
  every custom ClideIconPainter (Check, ChevronRight, ChevronDown,
  Dot, Folder, Gear, GitBranch, Plug, Search, Terminal, Warning).
- log_test: Logger.trace covered at minLevel.trace + filtered out
  at minLevel.info.
- services_bigger_test: DialogRouter.current getter; DialogHost
  widget rendered with backdrop + inner builder, then dismissed
  through the router. Plus FilesDropped subsystem/kind getters
  exercised through the existing notifyDropped test.

Coverage 89.08% -> 89.93%.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/kernel/src/log_test.dart

@@ -67,5 +67,18 @@ void main() {
       expect(a, hasLength(1));
       expect(b, hasLength(1));
     });
+
+    test('trace records emit at minLevel.trace + are filtered above it', () {
+      final got = <LogRecord>[];
+      final log = Logger(minLevel: LogLevel.trace, sinks: [got.add]);
+      log.trace('s', 'low-level detail');
+      expect(got, hasLength(1));
+      expect(got.first.level, LogLevel.trace);
+      // Same call at info-level is filtered.
+      got.clear();
+      final filtered = Logger(minLevel: LogLevel.info, sinks: [got.add]);
+      filtered.trace('s', 'still detail');
+      expect(got, isEmpty);
+    });
   });
 }