chore: reorganize test files into domain-specific subdirectories under tests/

Split the monolithic test directory into three tiers (unit, api, e2e) with a path-mirroring directory structure. Added corresponding Makefile targets (test-unit, test-api, test-e2e) and updated all documentation references (CLAUDE.md, README.md, testing-cicd.html, testing-framework.html, testing-make.html) to reflect the new layout and naming conventions.

tests/api/admin/containers/data.py

@@ -0,0 +1,18 @@
+# retoor <retoor@molodetz.nl>
+
+import requests
+from tests.conftest import BASE_URL
+from devplacepy.database import get_table
+
+
+def test_containers_admin_data_denied_for_non_admin(app_server, seeded_db):
+    s = requests.Session()
+    s.post(
+        f"{BASE_URL}/auth/login",
+        data={
+            "email": seeded_db["bob"]["email"],
+            "password": seeded_db["bob"]["password"],
+        },
+    )
+    r = s.get(f"{BASE_URL}/admin/containers/data", allow_redirects=False)
+    assert r.status_code in (302, 303, 403)

tests/api/admin/containers/index.py

@@ -0,0 +1,10 @@
+# retoor <retoor@molodetz.nl>
+
+import requests
+from tests.conftest import BASE_URL
+from devplacepy.database import get_table
+
+
+def test_containers_admin_page_requires_login(app_server):
+    r = requests.get(f"{BASE_URL}/admin/containers", allow_redirects=False)
+    assert r.status_code in (302, 303)