release: cut v1.2.1 — event-form polish

Version bumped to 1.2.1 / 10. No code changes beyond the version — 1.2.1 is
the reviewed-and-approved form polish: card design system, optional fields
with settings defaults, reworked reminders, OptionCard dialogs app-wide,
expressive theme on standard springs, direction-aware today jump, IME fix.
CHANGELOG [1.2.1] carries the details.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.2.1] — 2026-06-11
+
 ### Added
 - Optional event-form fields with user-controlled defaults: reminders,
   availability (busy/free), and visibility (default/public/private/
@@ -32,6 +34,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   springs
 - The jump-to-today slide is direction-aware (future → today slides in from
   the left, past → from the right)
+- `versionName`/`versionCode` bumped to 1.2.1 / 10
 
 ### Fixed
 - The keyboard no longer pans the whole event form; the screen stays