feat(deploy): V4 migration — add created_by to deployments

cameleer-server-app/src/main/resources/db/migration/V4__add_deployment_created_by.sql

@@ -0,0 +1,8 @@
+-- V4: add created_by column to deployments for audit trail
+-- Captures which user initiated a deployment. Nullable for backwards compatibility;
+-- pre-V4 historical deployments will have NULL.
+
+ALTER TABLE deployments
+    ADD COLUMN created_by TEXT REFERENCES users(user_id);
+
+CREATE INDEX idx_deployments_created_by ON deployments (created_by);

cameleer-server-app/src/test/java/com/cameleer/server/app/storage/V4DeploymentCreatedByMigrationIT.java

@@ -0,0 +1,53 @@
+package com.cameleer.server.app.storage;
+
+import com.cameleer.server.app.AbstractPostgresIT;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.jdbc.core.JdbcTemplate;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class V4DeploymentCreatedByMigrationIT extends AbstractPostgresIT {
+
+    @Autowired JdbcTemplate jdbc;
+
+    @Test
+    void created_by_column_exists_with_correct_type_and_nullable() {
+        List<Map<String, Object>> cols = jdbc.queryForList(
+            "SELECT column_name, data_type, is_nullable " +
+            "FROM information_schema.columns " +
+            "WHERE table_name = 'deployments' AND column_name = 'created_by'"
+        );
+        assertThat(cols).hasSize(1);
+        assertThat(cols.get(0)).containsEntry("data_type", "text");
+        assertThat(cols.get(0)).containsEntry("is_nullable", "YES");
+    }
+
+    @Test
+    void created_by_index_exists() {
+        Integer count = jdbc.queryForObject(
+            "SELECT count(*)::int FROM pg_indexes " +
+            "WHERE tablename = 'deployments' AND indexname = 'idx_deployments_created_by'",
+            Integer.class
+        );
+        assertThat(count).isEqualTo(1);
+    }
+
+    @Test
+    void created_by_has_fk_to_users() {
+        Integer count = jdbc.queryForObject(
+            "SELECT count(*)::int FROM information_schema.table_constraints tc " +
+            "JOIN information_schema.constraint_column_usage ccu " +
+            "  ON tc.constraint_name = ccu.constraint_name " +
+            "WHERE tc.table_name = 'deployments' " +
+            "  AND tc.constraint_type = 'FOREIGN KEY' " +
+            "  AND ccu.table_name = 'users' " +
+            "  AND ccu.column_name = 'user_id'",
+            Integer.class
+        );
+        assertThat(count).isGreaterThanOrEqualTo(1);
+    }
+}