docs: add Claude AI assistant rules and configuration

Add comprehensive rule documentation for AI-assisted development covering
authentication surfaces, outbound-call safety invariants, and other project
conventions to guide Claude's understanding of critical system behaviors.

tests/test_structure.py

@@ -9,7 +9,6 @@ through the shared data layer in services/call_persistence.py.
 
 import httpx
 import pytest
-from pydantic import SecretStr
 from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
 from sqlalchemy.pool import StaticPool
 
@@ -116,7 +115,9 @@ class TestInboundPolicy:
 
 @pytest.fixture
 async def client(monkeypatch):
-    monkeypatch.setattr(get_settings(), "api_token", SecretStr(""))
+    # Dev-owner mode: tokenless requests resolve to the owner. auth's DB
+    # session comes through the same get_db override below.
+    monkeypatch.setattr(get_settings().casdoor, "enabled", False)
 
     engine = create_async_engine(
         "sqlite+aiosqlite:///:memory:",