dissolve app/ into repo root (D-056)

Single Flutter package at the repo root. All code, tests, assets,
and platform directories moved from app/ to root. Package renamed
from clide_app to clide — all imports rewritten. Merged pubspec
combines core (ffi) and app (flutter, yaml, xterm) dependencies.
Makefile simplified: no APP_PRESENT conditionals, no cd, no daemon
lifecycle. 317 tests pass.

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

lib/widgets/src/clide_divider.dart

@@ -0,0 +1,23 @@
+import 'package:clide/kernel/src/theme/controller.dart';
+import 'package:flutter/widgets.dart';
+
+class ClideDivider extends StatelessWidget {
+  const ClideDivider({
+    super.key,
+    this.axis = Axis.horizontal,
+    this.thickness = 1,
+  });
+
+  final Axis axis;
+  final double thickness;
+
+  @override
+  Widget build(BuildContext context) {
+    final color = ClideTheme.of(context).surface.dividerColor;
+    return Container(
+      width: axis == Axis.vertical ? thickness : null,
+      height: axis == Axis.horizontal ? thickness : null,
+      color: color,
+    );
+  }
+}