keystroke mapper layer — intents, presets, when-clauses (T-117)

Build the upstream of every keyboard-driven feature: widgets bind
to typed Intents, the keymap resolves chord+context to an Intent,
and Flutter's Actions dispatches. The widget never touches a key.

Layers (low → high precedence):
  1. preset YAML in assets/keymaps/<preset>.yaml
  2. extension-registered command bindings (via
     KeymapService.registerCommandBinding from ExtensionManager)
  3. user file at <appDir>/keybindings.yaml
  4. settings JSON overlay at app.keymap.overrides

The when-clause grammar is a tiny recursive-descent parser over
boolean expressions on a named context bag — VS-Code style
`palette.open && !textInputFocused`. Producing services publish
scope flags via setScopeFlag.

Keys reference LogicalKeyboardKey.keyId (stable across keyboard
layouts), not the locale-aware keyLabel the consultant flagged.

Ships:
  - lib/kernel/src/keymap/{key_chord, when_clause, intents, keymap,
    keymap_service}.dart
  - assets/keymaps/default.yaml (the baseline preset)
  - 90+ unit tests covering parser precedence, layering precedence,
    scope evaluation, register/unregister, settings overlay,
    malformed-input tolerance
  - app.dart root handler routes through KeymapService → Actions
  - ExtensionManager mirrors every legacy defaultBinding into the
    keymap as a contribution layer

KeybindingResolver kept temporarily as a back-compat shim for
callers we haven't migrated yet; safe to delete once the last
caller goes through Actions.

Closes T-110 (consultant: scoped Shortcuts/Actions; off keyLabel).
Annotates T-23 with what's left for T-100. Unblocks T-64 / T-65 /
T-66 (preset data tickets).

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

lib/kernel/src/facade.dart

@@ -4,6 +4,7 @@ import 'dart:io';
 import 'package:clide/clide.dart';
 import 'package:clide/kernel/src/clipboard.dart';
 import 'package:clide/kernel/src/commands/keybindings.dart';
+import 'package:clide/kernel/src/keymap/keymap_service.dart';
 import 'package:clide/kernel/src/commands/palette.dart';
 import 'package:clide/kernel/src/commands/registry.dart';
 import 'package:clide/kernel/src/dialog.dart';
@@ -63,6 +64,7 @@ class KernelServices {
     required this.window,
     required this.toolchain,
     required this.scheduler,
+    required this.keymap,
   });
 
   final Logger log;
@@ -91,6 +93,7 @@ class KernelServices {
   final WindowControls window;
   final Toolchain toolchain;
   final SchedulerService scheduler;
+  final KeymapService keymap;
 
   static Future<KernelServices> boot({
     required Directory appDir,
@@ -132,6 +135,8 @@ class KernelServices {
     final arrangement = LayoutArrangement();
     final commands = CommandRegistry();
     final keybindings = KeybindingResolver();
+    final keymap = KeymapService(settings: settings, appDir: appDir);
+    await keymap.load();
     final palette = PaletteController(commands);
     final clipboard = ClideClipboard();
     final files = FileServices(events);
@@ -174,6 +179,7 @@ class KernelServices {
       commands: commands,
       palette: palette,
       keybindings: keybindings,
+      keymap: keymap,
       clipboard: clipboard,
       files: files,
       notify: notify,
@@ -218,6 +224,7 @@ class KernelServices {
       window: window,
       toolchain: tc,
       scheduler: scheduler,
+      keymap: keymap,
     );
   }
 
@@ -239,6 +246,7 @@ class KernelServices {
     project.dispose();
     extensions.dispose();
     await scheduler.dispose();
+    keymap.dispose();
     await log.dispose();
     messages.dispose();
     await events.dispose();