feat(auth): authentication module with multi-tenant isolation (RFC-001)

Introduce an always-on auth layer with auto-created admin on first boot,
multi-tenant isolation for threads/stores, and a full setup/login flow.

Backend
- JWT access tokens with `ver` field for stale-token rejection; bump on
  password/email change
- Password hashing, HttpOnly+Secure cookies (Secure derived from request
  scheme at runtime)
- CSRF middleware covering both REST and LangGraph routes
- IP-based login rate limiting (5 attempts / 5-min lockout) with bounded
  dict growth and X-Forwarded-For bypass fix
- Multi-worker-safe admin auto-creation (single DB write, WAL once)
- needs_setup + token_version on User model; SQLite schema migration
- Thread/store isolation by owner; orphan thread migration on first admin
  registration
- thread_id validated as UUID to prevent log injection
- CLI tool to reset admin password
- Decorator-based authz module extracted from auth core

Frontend
- Login and setup pages with SSR guard for needs_setup flow
- Account settings page (change password / email)
- AuthProvider + route guards; skips redirect when no users registered
- i18n (en-US / zh-CN) for auth surfaces
- Typed auth API client; parseAuthError unwraps FastAPI detail envelope

Infra & tooling
- Unified `serve.sh` with gateway mode + auto dep install
- Public PyPI uv.toml pin for CI compatibility
- Regenerated uv.lock with public index

Tests
- HTTP vs HTTPS cookie security tests
- Auth middleware, rate limiter, CSRF, setup flow coverage

backend/tests/test_client.py

@@ -59,18 +59,20 @@ class TestClientInit:
         assert client._subagent_enabled is False
         assert client._plan_mode is False
         assert client._agent_name is None
+        assert client._available_skills is None
         assert client._checkpointer is None
         assert client._agent is None
 
     def test_custom_params(self, mock_app_config):
         mock_middleware = MagicMock()
         with patch("deerflow.client.get_app_config", return_value=mock_app_config):
-            c = DeerFlowClient(model_name="gpt-4", thinking_enabled=False, subagent_enabled=True, plan_mode=True, agent_name="test-agent", middlewares=[mock_middleware])
+            c = DeerFlowClient(model_name="gpt-4", thinking_enabled=False, subagent_enabled=True, plan_mode=True, agent_name="test-agent", available_skills={"skill1", "skill2"}, middlewares=[mock_middleware])
         assert c._model_name == "gpt-4"
         assert c._thinking_enabled is False
         assert c._subagent_enabled is True
         assert c._plan_mode is True
         assert c._agent_name == "test-agent"
+        assert c._available_skills == {"skill1", "skill2"}
         assert c._middlewares == [mock_middleware]
 
     def test_invalid_agent_name(self, mock_app_config):
@@ -394,8 +396,10 @@ class TestEnsureAgent:
             patch("deerflow.client._build_middlewares", return_value=[]) as mock_build_middlewares,
             patch("deerflow.client.apply_prompt_template", return_value="prompt") as mock_apply_prompt,
             patch.object(client, "_get_tools", return_value=[]),
+            patch("deerflow.agents.checkpointer.get_checkpointer", return_value=MagicMock()),
         ):
             client._agent_name = "custom-agent"
+            client._available_skills = {"test_skill"}
             client._ensure_agent(config)
 
         assert client._agent is mock_agent
@@ -404,6 +408,7 @@ class TestEnsureAgent:
         assert mock_build_middlewares.call_args.kwargs.get("agent_name") == "custom-agent"
         mock_apply_prompt.assert_called_once()
         assert mock_apply_prompt.call_args.kwargs.get("agent_name") == "custom-agent"
+        assert mock_apply_prompt.call_args.kwargs.get("available_skills") == {"test_skill"}
 
     def test_uses_default_checkpointer_when_available(self, client):
         mock_agent = MagicMock()
@@ -441,6 +446,7 @@ class TestEnsureAgent:
             patch("deerflow.client._build_middlewares", side_effect=fake_build_middlewares),
             patch("deerflow.client.apply_prompt_template", return_value="prompt"),
             patch.object(client, "_get_tools", return_value=[]),
+            patch("deerflow.agents.checkpointer.get_checkpointer", return_value=MagicMock()),
         ):
             client._ensure_agent(config)
 
@@ -469,7 +475,7 @@ class TestEnsureAgent:
         """_ensure_agent does not recreate if config key unchanged."""
         mock_agent = MagicMock()
         client._agent = mock_agent
-        client._agent_config_key = (None, True, False, False)
+        client._agent_config_key = (None, True, False, False, None, None)
 
         config = client._get_runnable_config("t1")
         client._ensure_agent(config)
@@ -1276,6 +1282,7 @@ class TestScenarioAgentRecreation:
             patch("deerflow.client._build_middlewares", return_value=[]),
             patch("deerflow.client.apply_prompt_template", return_value="prompt"),
             patch.object(client, "_get_tools", return_value=[]),
+            patch("deerflow.agents.checkpointer.get_checkpointer", return_value=MagicMock()),
         ):
             client._ensure_agent(config_a)
             first_agent = client._agent
@@ -1303,6 +1310,7 @@ class TestScenarioAgentRecreation:
             patch("deerflow.client._build_middlewares", return_value=[]),
             patch("deerflow.client.apply_prompt_template", return_value="prompt"),
             patch.object(client, "_get_tools", return_value=[]),
+            patch("deerflow.agents.checkpointer.get_checkpointer", return_value=MagicMock()),
         ):
             client._ensure_agent(config)
             client._ensure_agent(config)
@@ -1327,6 +1335,7 @@ class TestScenarioAgentRecreation:
             patch("deerflow.client._build_middlewares", return_value=[]),
             patch("deerflow.client.apply_prompt_template", return_value="prompt"),
             patch.object(client, "_get_tools", return_value=[]),
+            patch("deerflow.agents.checkpointer.get_checkpointer", return_value=MagicMock()),
         ):
             client._ensure_agent(config)
             client.reset_agent()