v1.0.0

v1.0.0 — Initial public release

• WordPress.org-compatible plugin headers, GPL-2.0 license, readme.txt
• i18n via text domain 'migration-note'
• Lazy CSS enqueue (stylesheet only loads where the shortcode is used)
• 'note' shortcode attribute for freeform editorial text (no forced separator)
• 'migration_note_html' filter for theme-level output overrides