keyboard-operable ClideTappable + palette nav (T-100)

Plug widgets into the keymap layer landed in T-117.

ClideTappable:
  - Wrap in `Actions(ActivateIntent → onTap)` outside a `Focus` so
    dispatch from the focused context walks up and hits the action.
  - Add a focus ring via `tokens.globalFocus` (DecoratedBox foreground
    overlay, transparent border when unfocused, no layout shift).
  - Disabled (`onTap == null`) skips focus traversal and shows the
    forbidden cursor.

ClidePalette:
  - Register Actions for the four palette intents
    (selectNext / selectPrev / accept / dismiss).
  - Publish `palette.open` scope flag via `KeymapService.setScopeFlag`
    so when-clauses can scope future bindings to "palette only".
  - Highlight the selected row with `listItemSelectedBackground`;
    scroll it into view on nav.
  - `PaletteController` grows `selectedIndex` + `selectNext` /
    `selectPrevious` / `acceptSelected`; index resets on open /
    filter change.

Intents.dart drops the `ClideIntent` base — `ActivateIntent` and
`DismissIntent` come from Flutter; clide owns the palette and text-
scale and command-bridge subclasses. `parseIntentId('activate')` →
Flutter's class; same for dismiss. Widget code uses the canonical
Flutter Intent types where they fit.

App root grows a PaletteOpenIntent action that calls
`services.palette.open()`, completing the ctrl/cmd+shift+p path
end-to-end.

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

test/kernel/src/keymap/keymap_service_test.dart

@@ -8,6 +8,7 @@ import 'package:clide/kernel/src/keymap/key_chord.dart';
 import 'package:clide/kernel/src/keymap/keymap_service.dart';
 import 'package:clide/kernel/src/settings.dart';
 import 'package:flutter/services.dart';
+import 'package:flutter/widgets.dart' show ActivateIntent, DismissIntent;
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
@@ -136,8 +137,6 @@ void main() {
       expect(intent, isA<InvokeCommandIntent>());
       final invoke = intent as InvokeCommandIntent;
       expect(invoke.commandId, 'git.commit');
-      // `id` carries the command suffix for round-trip identification.
-      expect(invoke.id, 'command:git.commit');
     });
 
     test('honours a when-clause on the contribution', () async {

test/kernel/src/keymap/keymap_test.dart

@@ -4,6 +4,7 @@ library;
 import 'package:clide/kernel/src/keymap/intents.dart';
 import 'package:clide/kernel/src/keymap/key_chord.dart';
 import 'package:clide/kernel/src/keymap/keymap.dart';
+import 'package:flutter/widgets.dart' show ActivateIntent, DismissIntent;
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {