build(release): several apps released in one run (train:minor learn), their version commits pushed without the checks

The release tool and tool/with_signing_keys.sh take several apps, each with its version
after a colon or none, and release them one after another, each as alone, stopping at
the first that fails; the key script fetches every named app's key.

The pre-push hook skips tool/check.dart when a push brings release commits alone: the
release tool's chore(release) subject, an app's pubspec changed in its version line and
its texts of what's new, nothing else (tool/release_push.dart). Signatures are checked as
before, and CI still runs the checks. A release no longer costs a run of the checks.

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/release/release_push_test.dart

@@ -0,0 +1,80 @@
+import 'package:test/test.dart';
+
+import '../../tool/src/release/release_push.dart';
+import '../../tool/src/release/version.dart';
+
+void main() {
+  Commit release({
+    String subject = 'chore(release): train-v0.2.0',
+    List<String> files = const [
+      'apps/train/halkyon_train_flutter/pubspec.yaml',
+      'apps/train/halkyon_train_flutter/assets/whats_new/0.2.0.en.txt',
+      'apps/train/halkyon_train_flutter/assets/whats_new/0.2.0.de.txt',
+    ],
+  }) => Commit(hash: 'abc', subject: subject, body: 'Build 2.', files: files);
+
+  const versionOnly = ['-version: 0.1.0+1', '+version: 0.2.0+2'];
+
+  test('a release commit, the version and what is new alone, needs no '
+      'checks', () {
+    expect(releaseCommitProblem(release(), versionOnly), isNull);
+    expect(
+      releaseCommitProblem(
+        release(
+          subject: 'chore(release): todo-v0.1.1',
+          files: ['apps/todo/halkyon_todo_flutter/pubspec.yaml'],
+        ),
+        versionOnly,
+      ),
+      isNull,
+    );
+  });
+
+  test('anything else does: another subject, another file, or the pubspec '
+      'changed beyond its version', () {
+    expect(
+      releaseCommitProblem(release(subject: 'fix(train): a fix'), versionOnly),
+      isNotNull,
+    );
+    expect(
+      releaseCommitProblem(
+        release(subject: 'chore(release): train-v0.2.0 and more'),
+        versionOnly,
+      ),
+      isNotNull,
+    );
+    for (final file in [
+      'apps/train/halkyon_train_flutter/lib/main.dart',
+      'pubspec.lock',
+      'apps/train/halkyon_train_flutter/assets/whats_new/notes.md',
+      'tool/pre-push',
+    ]) {
+      expect(
+        releaseCommitProblem(
+          release(files: [...release().files, file]),
+          versionOnly,
+        ),
+        isNotNull,
+        reason: file,
+      );
+    }
+    expect(releaseCommitProblem(release(files: []), versionOnly), isNotNull);
+    expect(
+      releaseCommitProblem(release(), [...versionOnly, '+  http: ^1.0.0']),
+      isNotNull,
+    );
+  });
+
+  test('a push needs no checks only when it brings commits, all of them '
+      'release commits', () {
+    expect(onlyReleaseCommits(const []), isFalse);
+    expect(onlyReleaseCommits([(release(), versionOnly)]), isTrue);
+    expect(
+      onlyReleaseCommits([
+        (release(), versionOnly),
+        (release(subject: 'feat(learn): more'), versionOnly),
+      ]),
+      isFalse,
+    );
+  });
+}