0.2.34: manage exited status from the Capital Accounts view

The eNAV keeps listing exited members each quarter, so the admin needs
the exit control where the statements live:
- Capital Accounts table gains a Status column with the same
  Exited-badge / mark / undo flow as the Partners tab (keyed per
  investor+fund pair — marking any statement row marks them all)
- set_partner_exited now creates the access row (flag set) when a
  manually-entered investor has statements but no roster entry yet;
  clearing a never-set exit stays 404

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/tests/test_exited.py

@@ -89,11 +89,28 @@ def test_exited_member_excluded_from_rollup_committed(auth_client, session):
     assert row["committed_cents"] == 4_000_000_00
 
 
-def test_exited_requires_membership(auth_client, session):
+def test_exited_without_access_row(auth_client, session):
+    """A manually-entered investor may have statements but no access grant yet — marking
+    them exited from the Capital Accounts screen creates the roster row with the flag set.
+    Clearing an exit that was never set stays a 404."""
     entity, _ = _setup_fund(session)
-    stranger = make_user(session, username="stranger", role=UserRole.investor)
+    manual = make_user(session, username="manual-lp", role=UserRole.investor)
+
     resp = auth_client.put(
-        f"/api/entities/{entity.id}/partners/{stranger.id}/exited",
-        json={"exited_on": "2026-05-15"},
+        f"/api/entities/{entity.id}/partners/{manual.id}/exited",
+        json={"exited_on": None},
     )
     assert resp.status_code == 404
+
+    resp = auth_client.put(
+        f"/api/entities/{entity.id}/partners/{manual.id}/exited",
+        json={"exited_on": "2026-05-15"},
+    )
+    assert resp.status_code == 200, resp.text
+    assert resp.json()["exited_on"] == "2026-05-15"
+    access = session.exec(
+        select(EntityAccess).where(
+            EntityAccess.entity_id == entity.id, EntityAccess.user_id == manual.id
+        )
+    ).one()
+    assert str(access.exited_on) == "2026-05-15"