Release 1.0 notes + fixes: remove kc_phasen query, init $debug_output; add CHANGELOG and link from README

CHANGELOG.md

@@ -0,0 +1,16 @@
+# Changelog
+
+All notable changes to this project are documented in this file.
+
+## [1.0] - 2026-02-01
+### Added
+- Initial release of the KonfiCastle Workshop-Wahlen plugin (Admin backend, participant frontend, assignment logic, CSV export, teamer password management).
+- Shortcodes: `[konficastle_workshopwahl wahl=ID]`, `[konficastle_workshop_ergebnis wahl=ID]`.
+
+### Fixed
+- Removed query against non-existent table `kc_phasen`; phases are derived from `kc_wahlen.anzahl_einheiten`. See [includes/admin-workshops.php](includes/admin-workshops.php).
+- Initialized `$debug_output` to prevent PHP warning in frontend. See [includes/frontend-form.php](includes/frontend-form.php).
+
+### Notes
+- Database tables use WordPress prefix via `$wpdb->prefix`.
+- Force assignments have priority over automatic allocation.