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/posts/index.py

@@ -0,0 +1,30 @@
+# retoor <retoor@molodetz.nl>
+
+import time
+import requests
+from tests.conftest import BASE_URL
+from devplacepy.database import get_table
+JSON_content_negotiation = {"Accept": "application/json"}
+_counter_content_negotiation = [0]
+def _session_content_negotiation(password="secret123"):
+    _counter_content_negotiation[0] += 1
+    name = f"cn{int(time.time() * 1000)}{_counter_content_negotiation[0]}"
+    s = requests.Session()
+    s.post(
+        f"{BASE_URL}/auth/signup",
+        data={
+            "username": name,
+            "email": f"{name}@t.dev",
+            "password": password,
+            "confirm_password": password,
+        },
+        allow_redirects=True,
+    )
+    return s, name
+PUBLIC_PAGES = ["/feed", "/projects", "/gists", "/news", "/leaderboard", "/bugs"]
+
+
+def test_json_404_error_envelope(app_server):
+    r = requests.get(f"{BASE_URL}/posts/does-not-exist-xyz", headers=JSON_content_negotiation)
+    assert r.status_code == 404
+    assert r.json()["error"]["status"] == 404