feat(draw): wire the drawing card into the conversation — end to end (T-318)

The last wire: a DrawingMessage conversation item + the Claude-extension
subscriber on the `draw` channel (buildSvgDocument → inject), the
conversation renderer (DrawingCard), the fold/summary switches, the i18n
`drawing` label, and registering `clide draw` at boot (empty template
registry for now — primitive SVG works; d2/icon/compare/image handlers
plug in as they land). `clide draw --file doc.json` now renders a card in
the conversation. Render widget-tested; analyze + format clean across the
repo. Templates + per-object overlay remain; the CHANGELOG entry lands
with the user-complete feature.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/main.dart

@@ -39,6 +39,7 @@ import 'package:clide/builtin/claude/src/account_registry.dart';
 import 'package:clide/clide.dart' show clideVersion;
 import 'package:clide/src/daemon/claude_account_commands.dart';
 import 'package:clide/src/daemon/dispatcher.dart';
+import 'package:clide/src/daemon/draw_commands.dart';
 import 'package:clide/src/daemon/editor_commands.dart';
 import 'package:clide/src/daemon/files_commands.dart';
 import 'package:clide/src/daemon/git_commands.dart';
@@ -361,6 +362,24 @@ Future<void> main() async {
         return file.existsSync() ? file.absolute.path : null;
       },
     );
+    // `clide draw --file <doc>` — drive a drawing card into the Claude
+    // conversation (T-318, drive-half of D-6). Reads the JSON doc relative to
+    // workRoot, lowers it to SVG via the template registry (primitive svg now;
+    // d2/icon/compare/image handlers register as they land), then publishes a
+    // 'draw' message the Claude extension injects.
+    registerDrawCommands(
+      dispatcher,
+      () => kernelMessages?.publish,
+      registry: DrawingRegistry(),
+      readFile: (path) async {
+        final file = File(path.startsWith('/') ? path : '${workRoot.path}/$path');
+        try {
+          return file.existsSync() ? await file.readAsString() : null;
+        } catch (_) {
+          return null;
+        }
+      },
+    );
     // `clide claude account …` — manage per-repo Claude accounts (T-480, epic
     // T-476). Registry reads/writes go through the user-scope SettingsStore;
     // side-effects (respawn, login pane, --purge) are published on