refactor: move slow performance tests to extra test suite

Justfile

@@ -22,7 +22,7 @@ seed-database:
 start-database:
     docker compose up -d
 
-ci-dev: lint audit test
+ci-dev: lint audit test-fast
 
 gettext:
   mix gettext.extract
@@ -44,6 +44,18 @@ audit:
 test *args: install-dependencies
     mix test {{args}}
 
+# Run only fast tests (excludes slow/performance tests)
+test-fast *args: install-dependencies
+    mix test --exclude slow {{args}}
+
+# Run only slow/performance tests
+test-slow *args: install-dependencies
+    mix test --only slow {{args}}
+
+# Run all tests (fast + slow)
+test-all *args: install-dependencies
+    mix test {{args}}
+
 format:
     mix format