fix: remove unit tests redundant with e2e, fix test DB isolation

Remove 7 test files fully covered by e2e tests (admin, account, models,
API routes, integration MFA/OIDC, notifications). Trim 5 more files to
keep only edge cases not reachable via e2e.

Fix conftest to replace wiregui.db engine/session at import time so all
code uses the test database. Use session-scoped tables with per-test
savepoint isolation to prevent data leaking between tests.

tests/test_server_key.py

@@ -2,62 +2,59 @@
 
 import pytest
 
-from wiregui.db import async_session
 from wiregui.models.configuration import Configuration
 from wiregui.utils.server_key import get_server_public_key
-from sqlmodel import select
 
 
-@pytest.fixture(autouse=True)
-async def _snapshot_config():
-    """Snapshot and restore server_public_key around each test."""
-    async with async_session() as session:
-        c = (await session.execute(select(Configuration).limit(1))).scalar_one_or_none()
-        orig = c.server_public_key if c else None
-        cid = c.id if c else None
-
-    yield
-
-    if cid:
-        async with async_session() as session:
-            c = await session.get(Configuration, cid)
-            if c:
-                c.server_public_key = orig
-                session.add(c)
-                await session.commit()
-
-
-async def test_get_server_public_key_returns_key():
+async def test_get_server_public_key_returns_key(session, monkeypatch):
     """Returns the public key when configured."""
-    async with async_session() as session:
-        c = (await session.execute(select(Configuration).limit(1))).scalar_one_or_none()
-        c.server_public_key = "TestServerPubKey123456789012345678901234w="
-        session.add(c)
-        await session.commit()
+    from contextlib import asynccontextmanager
+
+    @asynccontextmanager
+    async def mock_session():
+        yield session
+
+    monkeypatch.setattr("wiregui.utils.server_key.async_session", mock_session)
+
+    c = Configuration(server_public_key="TestServerPubKey123456789012345678901234w=")
+    session.add(c)
+    await session.flush()
 
     result = await get_server_public_key()
     assert result == "TestServerPubKey123456789012345678901234w="
 
 
-async def test_get_server_public_key_raises_when_missing():
+async def test_get_server_public_key_raises_when_missing(session, monkeypatch):
     """Raises RuntimeError when server_public_key is None."""
-    async with async_session() as session:
-        c = (await session.execute(select(Configuration).limit(1))).scalar_one_or_none()
-        c.server_public_key = None
-        session.add(c)
-        await session.commit()
+    from contextlib import asynccontextmanager
+
+    @asynccontextmanager
+    async def mock_session():
+        yield session
+
+    monkeypatch.setattr("wiregui.utils.server_key.async_session", mock_session)
+
+    c = Configuration(server_public_key=None)
+    session.add(c)
+    await session.flush()
 
     with pytest.raises(RuntimeError, match="not configured"):
         await get_server_public_key()
 
 
-async def test_get_server_public_key_raises_when_empty_string():
+async def test_get_server_public_key_raises_when_empty_string(session, monkeypatch):
     """Raises RuntimeError when server_public_key is empty string."""
-    async with async_session() as session:
-        c = (await session.execute(select(Configuration).limit(1))).scalar_one_or_none()
-        c.server_public_key = ""
-        session.add(c)
-        await session.commit()
+    from contextlib import asynccontextmanager
+
+    @asynccontextmanager
+    async def mock_session():
+        yield session
+
+    monkeypatch.setattr("wiregui.utils.server_key.async_session", mock_session)
+
+    c = Configuration(server_public_key="")
+    session.add(c)
+    await session.flush()
 
     with pytest.raises(RuntimeError, match="not configured"):
-        await get_server_public_key()
+        await get_server_public_key()