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/extensions_manager.dart

@@ -14,6 +14,7 @@ import 'package:clide/kernel/src/files.dart';
 import 'package:clide/kernel/src/focus.dart';
 import 'package:clide/kernel/src/i18n/i18n.dart';
 import 'package:clide/kernel/src/ipc/client.dart';
+import 'package:clide/kernel/src/keymap/keymap_service.dart';
 import 'package:clide/kernel/src/log.dart';
 import 'package:clide/kernel/src/net.dart';
 import 'package:clide/kernel/src/notify.dart';
@@ -40,6 +41,7 @@ class ExtensionManager extends ChangeNotifier {
     required this.commands,
     required this.palette,
     required this.keybindings,
+    required this.keymap,
     required this.clipboard,
     required this.files,
     required this.notify,
@@ -64,6 +66,7 @@ class ExtensionManager extends ChangeNotifier {
   final CommandRegistry commands;
   final PaletteController palette;
   final KeybindingResolver keybindings;
+  final KeymapService keymap;
   final ClideClipboard clipboard;
   final FileServices files;
   final Notifications notify;
@@ -171,7 +174,11 @@ class ExtensionManager extends ChangeNotifier {
         commands.register(cmd);
         final binding = cmd.defaultBinding;
         if (binding != null) {
+          // Legacy KeybindingResolver still wired for back-compat
+          // until all callers migrate; the keymap layer is the
+          // canonical home for chord → command bindings (T-117).
           keybindings.bind(Keybinding.parse(binding), cmd.command);
+          keymap.registerCommandBinding(binding, cmd.command);
         }
       case TrayItemContribution t:
         tray.add(t);
@@ -194,6 +201,7 @@ class ExtensionManager extends ChangeNotifier {
         if (binding != null) {
           keybindings.unbind(Keybinding.parse(binding));
         }
+        keymap.unregisterCommandBindings(cmd.command);
       case TrayItemContribution t:
         tray.remove(t.id);
       case LayoutPresetContribution _: