chore: rename project Roundtable → Steward

Renames the Python package directory, CLI command, env var prefix,
docker-compose service/container/image, Postgres role/db, and all
visible branding. Marketing form is "Fabled Steward".

Clean break from the previous rebrand: drops the fabledscryer→roundtable
import shim in __init__.py and the FABLEDSCRYER_* env var fallback in
config.py and migrations/env.py. Env vars are now STEWARD_* only.

Heads-up for existing deployments:
- Postgres user/db renamed fabledscryer → steward in docker-compose.yml.
  Existing volumes need the role/db renamed inside Postgres, or override
  POSTGRES_USER/POSTGRES_DB to keep the old names.
- Host-agent systemd unit is now steward-agent.service. Existing agents
  keep running under the old name; reinstall to switch.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/test_auth.py

@@ -1,7 +1,7 @@
 import pytest
 import bcrypt
 from unittest.mock import AsyncMock, patch
-from roundtable.models.users import User, UserRole
+from steward.models.users import User, UserRole
 
 
 def make_user(role=UserRole.admin):
@@ -23,7 +23,7 @@ async def test_login_page_returns_200(client):
 
 @pytest.mark.asyncio
 async def test_login_redirects_to_setup_when_no_users(client, app):
-    with patch("roundtable.auth.routes.get_user_count", new=AsyncMock(return_value=0)):
+    with patch("steward.auth.routes.get_user_count", new=AsyncMock(return_value=0)):
         response = await client.get("/login")
     assert response.status_code == 302
     assert "/setup" in response.headers["Location"]
@@ -32,8 +32,8 @@ async def test_login_redirects_to_setup_when_no_users(client, app):
 @pytest.mark.asyncio
 async def test_login_success_redirects_to_dashboard(client, app):
     user = make_user()
-    with patch("roundtable.auth.routes.get_user_count", new=AsyncMock(return_value=1)), \
-         patch("roundtable.auth.routes.get_user_by_username", new=AsyncMock(return_value=user)):
+    with patch("steward.auth.routes.get_user_count", new=AsyncMock(return_value=1)), \
+         patch("steward.auth.routes.get_user_by_username", new=AsyncMock(return_value=user)):
         response = await client.post("/login", form={"username": "admin", "password": "password"})
     assert response.status_code == 302
     assert "/" in response.headers["Location"]
@@ -42,8 +42,8 @@ async def test_login_success_redirects_to_dashboard(client, app):
 @pytest.mark.asyncio
 async def test_login_failure_returns_400(client, app):
     user = make_user()
-    with patch("roundtable.auth.routes.get_user_count", new=AsyncMock(return_value=1)), \
-         patch("roundtable.auth.routes.get_user_by_username", new=AsyncMock(return_value=user)):
+    with patch("steward.auth.routes.get_user_count", new=AsyncMock(return_value=1)), \
+         patch("steward.auth.routes.get_user_by_username", new=AsyncMock(return_value=user)):
         response = await client.post("/login", form={"username": "admin", "password": "wrong"})
     assert response.status_code == 400