feat(cli): show changelog entries before running upgrades

ts/upgrade-changelog.ts

@@ -0,0 +1,16 @@
+import { SmartChangelog } from 'npm:@push.rocks/smartchangelog@^0.1.0';
+
+export const renderUpgradeChangelog = (
+  changelogMarkdown: string,
+  currentVersion: string,
+  latestVersion: string,
+): string => {
+  const changelog = SmartChangelog.fromMarkdown(changelogMarkdown);
+  const entries = changelog.getEntriesBetween(currentVersion, latestVersion);
+
+  if (entries.length === 0) {
+    return '';
+  }
+
+  return entries.map((entry) => entry.toCliString()).join('\n\n');
+};