feat(campaigns): add pending_approval state to campaign domain entity

backend/tests/test_campaign_entity.py

@@ -173,3 +173,55 @@ def test_from_orm_handles_none_tags():
     orm.tags = None
     e = CampaignEntity.from_orm(orm)
     assert e.tags == []
+
+
+# ── 9. Submit for approval ────────────────────────────────────────────
+
+
+def test_submit_for_approval_from_draft_with_tests_success():
+    e = _entity("draft", test_count=1)
+    e.submit_for_approval()
+    assert e.status == CampaignStatus.pending_approval
+
+
+def test_submit_for_approval_from_draft_with_zero_tests_raises():
+    e = _entity("draft", test_count=0)
+    with pytest.raises(BusinessRuleViolation, match="at least one test"):
+        e.submit_for_approval()
+    assert e.status == CampaignStatus.draft
+
+
+def test_submit_for_approval_from_active_raises():
+    e = _entity("active", test_count=1)
+    with pytest.raises(InvalidStateTransition):
+        e.submit_for_approval()
+
+
+# ── 10. Approve ────────────────────────────────────────────────────────
+
+
+def test_approve_from_pending_approval_success():
+    e = _entity("pending_approval", test_count=1)
+    e.approve()
+    assert e.status == CampaignStatus.active
+
+
+def test_approve_from_draft_raises():
+    e = _entity("draft", test_count=1)
+    with pytest.raises(InvalidStateTransition):
+        e.approve()
+
+
+# ── 11. Reject ─────────────────────────────────────────────────────────
+
+
+def test_reject_from_pending_approval_returns_to_draft():
+    e = _entity("pending_approval", test_count=1)
+    e.reject()
+    assert e.status == CampaignStatus.draft
+
+
+def test_reject_from_draft_raises():
+    e = _entity("draft", test_count=1)
+    with pytest.raises(InvalidStateTransition):
+        e.reject()