feat: add account management, email verification, AI fixes, and user guides

- Profile settings, account transfer, delete/leave account flows
- Email verification with JWT tokens and Resend integration
- AI assistant/copilot fixes: markdown rendering, shared RAG helpers,
  token tracking, input refocus, model_validate usage
- User guides hub + detail pages with 13 topic guides
- Sidebar and top bar navigation for guides

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/tests/test_auth_profile.py

@@ -0,0 +1,90 @@
+"""Tests for PATCH /auth/me profile update endpoint."""
+
+import pytest
+from httpx import AsyncClient
+
+
+@pytest.mark.asyncio
+class TestProfileUpdate:
+    """Test profile update via PATCH /auth/me."""
+
+    async def test_update_name(self, client: AsyncClient, auth_headers: dict):
+        """Name update works without password."""
+        response = await client.patch(
+            "/api/v1/auth/me",
+            json={"name": "New Name"},
+            headers=auth_headers,
+        )
+        assert response.status_code == 200
+        assert response.json()["name"] == "New Name"
+
+    async def test_update_email_with_password(self, client: AsyncClient, auth_headers: dict):
+        """Email change with correct password succeeds."""
+        response = await client.patch(
+            "/api/v1/auth/me",
+            json={"email": "newemail@example.com", "current_password": "TestPassword123!"},
+            headers=auth_headers,
+        )
+        assert response.status_code == 200
+        assert response.json()["email"] == "newemail@example.com"
+
+    async def test_update_email_without_password(self, client: AsyncClient, auth_headers: dict):
+        """Email change without password returns 400."""
+        response = await client.patch(
+            "/api/v1/auth/me",
+            json={"email": "newemail@example.com"},
+            headers=auth_headers,
+        )
+        assert response.status_code == 400
+        assert "password" in response.json()["detail"].lower()
+
+    async def test_update_email_wrong_password(self, client: AsyncClient, auth_headers: dict):
+        """Email change with wrong password returns 401."""
+        response = await client.patch(
+            "/api/v1/auth/me",
+            json={"email": "newemail@example.com", "current_password": "WrongPassword123!"},
+            headers=auth_headers,
+        )
+        assert response.status_code == 401
+
+    async def test_update_email_duplicate(self, client: AsyncClient, auth_headers: dict):
+        """Email change to existing email returns 400."""
+        # Register second user
+        await client.post("/api/v1/auth/register", json={
+            "email": "other@example.com",
+            "password": "TestPassword123!",
+            "name": "Other User",
+        })
+
+        response = await client.patch(
+            "/api/v1/auth/me",
+            json={"email": "other@example.com", "current_password": "TestPassword123!"},
+            headers=auth_headers,
+        )
+        assert response.status_code == 400
+        assert "already registered" in response.json()["detail"].lower()
+
+    async def test_get_me_returns_updated_name(self, client: AsyncClient, auth_headers: dict):
+        """GET /me reflects the updated profile."""
+        await client.patch(
+            "/api/v1/auth/me",
+            json={"name": "Updated User"},
+            headers=auth_headers,
+        )
+        response = await client.get("/api/v1/auth/me", headers=auth_headers)
+        assert response.status_code == 200
+        assert response.json()["name"] == "Updated User"
+
+    async def test_no_changes_returns_current_user(self, client: AsyncClient, auth_headers: dict):
+        """Empty update returns current user without error."""
+        response = await client.patch(
+            "/api/v1/auth/me",
+            json={},
+            headers=auth_headers,
+        )
+        assert response.status_code == 200
+
+    async def test_unauthenticated(self, client: AsyncClient):
+        """Unauthenticated request returns 401."""
+        response = await client.patch("/api/v1/auth/me", json={"name": "X"})
+        assert response.status_code == 401