fix: cast the nullable uuid so Postgres can type the existence check

createTopic answered 500: 'could not determine data type of parameter $2'.
The uniqueness check reads

  WHERE normalized_name = :name AND (:except IS NULL OR id <> :except)

and on a create there is no id to exclude, so :except is null. Postgres infers
a parameter's type from how it is used, and `IS NULL` tells it nothing — with
the other use behind an OR it never gets a second chance.

Casting both uses to uuid gives it the type without changing the predicate.

Project creation passed the same code path only because it never reaches
slugTaken: a draft opens with no slug, so the check is skipped. The topic path
runs it on every create.

src/adapter/outbound/persistence-jpa/src/main/java/dev/caskeleton/adapter/outbound/persistence/techlog/management/JdbcProjectRepositoryAdapter.java

@@ -216,7 +216,7 @@ public class JdbcProjectRepositoryAdapter implements ProjectRepositoryPort {
         jdbcClient
             .sql(
                 "SELECT EXISTS (SELECT 1 FROM project WHERE slug = :slug"
-                    + " AND (:except IS NULL OR id <> :except))")
+                    + " AND (CAST(:except AS uuid) IS NULL OR id <> CAST(:except AS uuid)))")
             .param("slug", slug)
             .param("except", exceptId)
             .query(Boolean.class)

src/adapter/outbound/persistence-jpa/src/main/java/dev/caskeleton/adapter/outbound/persistence/techlog/management/JdbcTopicRepositoryAdapter.java

@@ -143,7 +143,7 @@ public class JdbcTopicRepositoryAdapter implements TopicRepositoryPort {
         jdbcClient
             .sql(
                 "SELECT EXISTS (SELECT 1 FROM topic WHERE normalized_name = :name"
-                    + " AND (:except IS NULL OR id <> :except))")
+                    + " AND (CAST(:except AS uuid) IS NULL OR id <> CAST(:except AS uuid)))")
             .param("name", normalizedName)
             .param("except", exceptId)
             .query(Boolean.class)
@@ -156,7 +156,7 @@ public class JdbcTopicRepositoryAdapter implements TopicRepositoryPort {
         jdbcClient
             .sql(
                 "SELECT EXISTS (SELECT 1 FROM topic WHERE slug = :slug"
-                    + " AND (:except IS NULL OR id <> :except))")
+                    + " AND (CAST(:except AS uuid) IS NULL OR id <> CAST(:except AS uuid)))")
             .param("slug", slug)
             .param("except", exceptId)
             .query(Boolean.class)