fix(ps-cache-kotlin): use psql -c instead of heredoc for schema setup (#125)

docker exec ... psql -f- <<'SQL' doesn't work reliably because
docker exec doesn't forward stdin from heredocs by default.
Use psql -c "..." which works in all shells.

Also add sleep 3 to wait for Postgres readiness.

Signed-off-by: slayerjain <shubhamkjain@outlook.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: slayerjain

ps-cache-kotlin/README.md

@@ -59,17 +59,19 @@ docker run -d --name pg-demo \
   -e POSTGRES_DB=testdb \
   -p 5432:5432 postgres:16
 
+# Wait for Postgres to be ready
+sleep 3
+
 # Create the schema and seed data
-docker exec pg-demo psql -U postgres -d testdb -f- <<'SQL'
-CREATE SCHEMA IF NOT EXISTS travelcard;
-CREATE TABLE IF NOT EXISTS travelcard.travel_account (
+docker exec pg-demo psql -U postgres -d testdb -c "
+  CREATE SCHEMA IF NOT EXISTS travelcard;
+  CREATE TABLE IF NOT EXISTS travelcard.travel_account (
     id SERIAL PRIMARY KEY, member_id INT NOT NULL UNIQUE,
     name TEXT NOT NULL, balance INT NOT NULL DEFAULT 0);
-INSERT INTO travelcard.travel_account (member_id, name, balance) VALUES
+  INSERT INTO travelcard.travel_account (member_id, name, balance) VALUES
     (19, 'Alice', 1000), (23, 'Bob', 2500),
     (31, 'Charlie', 500), (42, 'Diana', 7500)
-ON CONFLICT (member_id) DO NOTHING;
-SQL
+  ON CONFLICT (member_id) DO NOTHING;"
 
 # Build
 mvn package -DskipTests -q