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/unit/push.py

@@ -0,0 +1,50 @@
+# retoor <retoor@molodetz.nl>
+
+import uuid
+import requests
+from tests.conftest import BASE_URL
+def _session_push():
+    s = requests.Session()
+    name = f"push_{uuid.uuid4().hex[:10]}"
+    s.post(
+        f"{BASE_URL}/auth/signup",
+        data={
+            "username": name,
+            "email": f"{name}@test.dev",
+            "password": "secret123",
+            "confirm_password": "secret123",
+        },
+        allow_redirects=True,
+    )
+    return s
+
+
+def test_browser_base64_is_url_safe_unpadded():
+    import base64
+    from devplacepy import push
+
+    encoded = push.browser_base64(b"\xff\xfe\x00 hello")
+    assert "=" not in encoded
+    assert "+" not in encoded and "/" not in encoded
+    assert base64.urlsafe_b64decode(encoded + "==") == b"\xff\xfe\x00 hello"
+
+
+def test_hkdf_returns_requested_length():
+    from devplacepy import push
+
+    derived = push.hkdf(b"input-key-material", b"salt", b"info", 16)
+    assert isinstance(derived, bytes)
+    assert len(derived) == 16
+
+
+def test_public_key_standard_b64_non_empty():
+    from devplacepy import push
+
+    assert push.public_key_standard_b64()
+
+
+def test_create_notification_authorization_is_jwt():
+    from devplacepy import push
+
+    token = push.create_notification_authorization("https://push.example.com/endpoint")
+    assert token.count(".") == 2