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>

test/kernel/src/commands/registry_test.dart

@@ -0,0 +1,51 @@
+import 'package:clide/clide.dart';
+import 'package:clide/extension/extension.dart';
+import 'package:clide/kernel/kernel.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+CommandContribution _cmd(String name, Future<IpcResponse> Function() run) =>
+    CommandContribution(
+      id: name,
+      command: name,
+      title: 'cmd $name',
+      run: (_) => run(),
+    );
+
+void main() {
+  group('CommandRegistry', () {
+    test('register exposes the command; all enumerates', () {
+      final r = CommandRegistry();
+      r.register(_cmd('a', () async => IpcResponse.ok(id: '', data: const {})));
+      r.register(_cmd('b', () async => IpcResponse.ok(id: '', data: const {})));
+      expect(r.all.map((c) => c.command).toList(), ['a', 'b']);
+      expect(r.get('a'), isNotNull);
+    });
+
+    test('execute returns the handler response', () async {
+      final r = CommandRegistry();
+      r.register(
+        _cmd(
+          'ping',
+          () async => IpcResponse.ok(id: '', data: const {'pong': true}),
+        ),
+      );
+      final resp = await r.execute('ping');
+      expect(resp.ok, true);
+      expect(resp.data['pong'], true);
+    });
+
+    test('execute on unknown returns NotFound error', () async {
+      final r = CommandRegistry();
+      final resp = await r.execute('missing');
+      expect(resp.ok, false);
+      expect(resp.error!.code, IpcExitCode.notFound);
+    });
+
+    test('unregister removes the command', () {
+      final r = CommandRegistry();
+      r.register(_cmd('x', () async => IpcResponse.ok(id: '', data: const {})));
+      r.unregister('x');
+      expect(r.get('x'), isNull);
+    });
+  });
+}