v0.1.20 - Even composer fields on laptops & add-success modal

- Throughput: even three-across layout for the "Add a packing run" fields
  on laptop widths so placeholders stay readable in the narrow content band
- Throughput: centred "Added" confirmation modal with in-card confetti on
  save (3s), composer clears for the next entry
- Fix stray character in changelog.ts type comment

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/changelog.ts

@@ -8,7 +8,7 @@ import packageInfo from '../../package.json';
  */
 export type ChangelogEntry = {
   version: string;
-  /** ISO date (YYYY-MM-DD) the version shipped. */a
+  /** ISO date (YYYY-MM-DD) the version shipped. */
   date: string;
   highlights: string[];
 };
@@ -17,6 +17,14 @@ export type ChangelogEntry = {
 export const APP_VERSION: string = packageInfo.version;
 
 export const changelog: ChangelogEntry[] = [
+  {
+    version: '0.1.20',
+    date: '2026-06-13',
+    highlights: [
+      'App - Improvements',
+      'App - Bug fixes'
+    ]
+  },
   {
     version: '0.1.18',
     date: '2026-06-12',