feat(deploy): the CI runner's window by hand, halkyon-ci-now (ADR 0039, D6)

Rests the heavy sidecars, runs every queued job, then stops the runner and
starts the sidecars again however it ends; from melchior through
systemd-run, so a closed laptop doesn't end it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

test/deploy/runner_test.dart

@@ -154,6 +154,48 @@ void main() {
     });
   });
 
+  group('a window by hand (halkyon-ci-now)', () {
+    final script = read('deploy/runner/ci-now.sh');
+
+    test('rests the heavy sidecars around the runner, unless asked to keep '
+        'them', () {
+      expect(script, contains('systemctl start halkyon-night'));
+      expect(script, contains('systemctl start halkyon-morning'));
+      expect(script, contains('--keep-sidecars'));
+    });
+
+    test('stops the runner and starts the sidecars again however it ends: '
+        'done, interrupted, stopped or its SSH session gone', () {
+      final trap = RegExp(
+        r'^trap (\S+) (.*)$',
+        multiLine: true,
+      ).firstMatch(script);
+      expect(trap, isNotNull);
+      expect(trap![2]!.split(' '), containsAll(['EXIT', 'INT', 'TERM', 'HUP']));
+      final restore = RegExp(
+        '^${trap[1]}\\(\\) \\{([^}]*)\\}',
+        multiLine: true,
+      ).firstMatch(script)![1]!;
+      expect(restore, contains('systemctl stop forgejo-runner'));
+      expect(restore, contains('systemctl start halkyon-morning'));
+    });
+
+    test('leaves the nightly window alone: refuses while the runner runs', () {
+      expect(script, contains('systemctl is-active --quiet forgejo-runner'));
+    });
+
+    test(
+      "is installed by host step 7, root's own, never deploy's checkout",
+      () {
+        final readme = read('deploy/host/README.md');
+        expect(
+          readme,
+          contains('deploy/runner/ci-now.sh /usr/local/sbin/halkyon-ci-now'),
+        );
+      },
+    );
+  });
+
   group('the workflow', () {
     final workflow = loadYaml(read('.forgejo/workflows/ci.yaml')) as YamlMap;
     final jobs = workflow['jobs'] as YamlMap;