feat(ci): capture crash evidence as artifacts when a run wedges (T-436)

Closes the observability loop: the log + breadcrumb + watchdog files are now
collected by CI so a wedged run leaves downloadable evidence instead of
nothing.

- logDirectory(): CLIDE_LOG_DIR overrides the per-platform default, so CI can
  point the logs at an uploadable workspace dir (and tests at a temp dir).
  Now takes an injectable env map; tested.
- test_app.dart: when CLIDE_LOG_DIR is set, the testmode harness tees its
  logger to a FileLogSink + spawns the watchdog (off by default — normal
  run-testmode keeps the stderr-only path, no isolate). _say breadcrumbs each
  test into the file.
- conpty_orphan_probe.dart: with CLIDE_LOG_DIR set it passes a verbose PtyLog,
  so when soak-conpty-kill.ps1 force-kills the parent, the reader/waiter
  isolates' LAST crumb is fsynced to disk — naming what the wedged isolate was
  doing at the instant of death.
- bundle-smoke job: runs the real release app with CLIDE_LOG=debug +
  CLIDE_LOG_DIR, uploads clide-logs (watchdog heartbeat/sample + FileLogSink)
  in an always() step.
- windows-soak kill-probe job: sets CLIDE_LOG_DIR, uploads the FFI crumbs.

Coverage gate 95.08%.

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

lib/test_app.dart

@@ -31,6 +31,7 @@ import 'kernel/kernel.dart';
 import 'src/pty/ffi/libc.dart' as libc;
 import 'src/daemon/pane_commands.dart';
 import 'src/ipc/envelope.dart';
+import 'src/ipc/paths.dart' show logDirectory;
 import 'src/panes/event_sink.dart';
 import 'src/panes/registry.dart';
 import 'src/daemon/dispatcher.dart';
@@ -59,6 +60,7 @@ class _ClideTestAppState extends State<ClideTestApp> {
   @override
   void initState() {
     super.initState();
+    _attachCrashLogging();
     WidgetsBinding.instance.addPostFrameCallback((_) => _runTests());
     Timer(_timeout, () {
       _say('timeout reached — exiting');
@@ -66,6 +68,28 @@ class _ClideTestAppState extends State<ClideTestApp> {
     });
   }
 
+  /// Opt-in crash evidence for testmode (T-436): when `CLIDE_LOG_DIR` is set
+  /// (CI / a manual Windows repro), tee this harness's logger to a
+  /// FileLogSink and spawn the watchdog, so a wedged testmode run leaves the
+  /// same log + watchdog files the real app would. `_say` breadcrumbs each
+  /// test through the logger, so they land in the file too. Off by default —
+  /// normal `make run-testmode` keeps the stderr-only path, no isolate.
+  void _attachCrashLogging() {
+    final dir = Platform.environment['CLIDE_LOG_DIR'];
+    if (dir == null || dir.isEmpty) return;
+    final logDir = logDirectory();
+    try {
+      _logger.addSink(FileLogSink(dir: Directory(logDir)).call);
+    } catch (_) {}
+    unawaited(_spawnWatchdog(logDir));
+  }
+
+  Future<void> _spawnWatchdog(String logDir) async {
+    try {
+      await Isolate.spawn(watchdogEntry, ('$logDir/clide-watchdog.log', 500, 2000));
+    } catch (_) {}
+  }
+
   Future<void> _runTests() async {
     const workspace = String.fromEnvironment('CLIDE_PROJECT');
     const category = String.fromEnvironment('CLIDE_TESTMODE');