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/kernel/src/theme/semantic.dart

@@ -0,0 +1,40 @@
+import 'dart:ui';
+
+import 'package:flutter/foundation.dart';
+
+@immutable
+class SemanticRoles {
+  const SemanticRoles(this._roles);
+  final Map<String, Color> _roles;
+
+  Color? lookup(String role) => _roles[role];
+  Iterable<String> get roles => _roles.keys;
+}
+
+abstract class SemanticKeys {
+  static const mainchrome = 'mainchrome';
+  static const calltoaction = 'calltoaction';
+  static const focus = 'focus';
+  static const background = 'background';
+  static const surface = 'surface';
+  static const text = 'text';
+  static const textMuted = 'text_muted';
+  static const success = 'success';
+  static const warning = 'warning';
+  static const error = 'error';
+  static const info = 'info';
+
+  static const all = <String>[
+    mainchrome,
+    calltoaction,
+    focus,
+    background,
+    surface,
+    text,
+    textMuted,
+    success,
+    warning,
+    error,
+    info,
+  ];
+}