Remove hardcoded USE statement from feedback schema migration

001_init.sql opened with USE `nachklang-feedback`, contradicting its own
documented apply instructions (mysql ... <FEEDBACK_DB> < 001_init.sql,
which already selects the database via the command line). Following the
file's own usage note literally would fail unless a database happened to
be named exactly nachklang-feedback rather than whatever FEEDBACK_DB is
configured to in .env.

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

sql/feedback/001_init.sql

@@ -6,8 +6,10 @@
 --
 -- Apply with e.g.:
 --   mysql -h <DB_HOST> -u <DB_USER> -p <FEEDBACK_DB> < 001_init.sql
-
+--
-USE `nachklang-feedback`;
+-- Deliberately no USE statement here: the target database is selected via
+-- the mysql command line above (whatever FEEDBACK_DB is actually named in
+-- .env), not hardcoded to a literal schema name.
 
 -- 1. events -------------------------------------------------------------
 CREATE TABLE events (