scaffold Flutter app — kernel, extensions, widgets, Tier 0 built-ins

First real content under app/. Lays the whole Tier 0 foundation in one
commit because the pieces depend on each other circularly (kernel →
extension → widgets → built-ins all reference types from the layer
below); splitting would leave intermediate commits that don't compile.

Key shapes:

  * bare WidgetsApp root — no Material, no Cupertino, no Scaffold.
    ClideTheme InheritedWidget is the only source of tokens.
  * ClideKernel InheritedWidget aggregates 18 services (settings,
    project, extensions, theme, panels, events, ipc, commands +
    palette + keybindings, clipboard, files, notify, dialog, tray,
    secrets, os, net, focus, log, i18n). ExtensionContext exposes
    them through a stable interface.
  * ClideExtension + sealed ContributionPoint hierarchy (Tab,
    StatusItem, Toolbar, Command, TrayItem, LayoutPreset). One
    manifest ships N contributions into kernel slots.
  * Three-tier theme pipeline: palette (named colors) → semantic
    roles → ~60 surface tokens. Defaults at each layer so legacy
    palette-only themes produce a complete SurfaceTokens.
  * A11y baked in from day one — every interactive primitive wraps
    in Semantics(label:, hint:, button:); ensureSemantics() at boot;
    theme/contrast.dart helper exposes token pairs for the WCAG
    gate in the a11y test suite.
  * i18n ported from fframe's L10n pattern (text-driven, namespaced
    JSON catalogs, caller-supplied placeholders) with a proper
    locale fallback chain (exact → language → default → placeholder)
    fframe lacks.
  * Four Tier-0 built-ins live (default-layout, welcome, ipc-status,
    theme-picker) plus 17 id-reserving stubs so later tiers fill in
    without rename churn.

.gitignore extended to cover app/ sub-package artefacts and the
Playwright harness scratch dirs.

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

app/pubspec.yaml

@@ -0,0 +1,55 @@
+# clide_app — Flutter desktop UI.
+#
+# Renders clide's IDE surfaces; depends on the root `clide` Dart core
+# package (shared with the CLI + daemon). Prefer-zero-deps; every
+# third-party entry below is exact-pinned and justified. No carets.
+
+name: clide_app
+description: >-
+  Flutter desktop IDE for Claude Code — renders the UI. Talks to the
+  Dart core (CLI + daemon) via IPC; all PTY/subprocess/filesystem work
+  lives in the daemon (ADR 0005).
+publish_to: none
+version: 2.0.0-dev
+repository: https://git.schweitz.net/jpmschweitzer/clide
+
+environment:
+  sdk: ">=3.5.0 <4.0.0"
+  flutter: ">=3.19.0"
+
+dependencies:
+  flutter:
+    sdk: flutter
+
+  # Dart core — shared types, IPC protocol, anything CLI + daemon + app
+  # all import. Kept Flutter-free so `dart compile exe` produces a lean
+  # static binary (see ADR 0005).
+  clide:
+    path: ../
+
+  # YAML — the one justified exception to prefer-zero-deps. Dart-team
+  # maintained, used for theme files and extension manifests.
+  yaml: 3.1.3
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+  flutter_lints: 6.0.0
+
+  # Integration tests for the real-app startup-regression gate.
+  integration_test:
+    sdk: flutter
+
+  # Mocks at IO/IPC boundaries; hand-rolled fakes for ChangeNotifiers.
+  mocktail: 1.0.4
+
+  # Golden-test framework (Ahem font, cross-platform pixel stability).
+  # Used only for widget primitives, not compositions.
+  alchemist: 0.12.1
+
+flutter:
+  uses-material-design: false
+
+  assets:
+    - lib/kernel/src/theme/themes/
+    - lib/kernel/src/i18n/catalog/