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/ten31portal/routers/entity_router.py

@@ -171,16 +171,26 @@ def set_partner_exited(
     Their statements and documents stay; the portal shows an Exited badge instead of a
     phantom -100% and drops the position from portfolio and fund committed totals.
     """
+    if session.get(Entity, entity_id) is None:
+        raise HTTPException(status_code=404, detail="Entity not found")
+    member = session.get(User, user_id)
+    if member is None or member.role != UserRole.investor:
+        raise HTTPException(status_code=400, detail="Only investor members can be marked exited")
+
     access = session.exec(
         select(EntityAccess).where(
             EntityAccess.entity_id == entity_id, EntityAccess.user_id == user_id
         )
     ).first()
     if access is None:
-        raise HTTPException(status_code=404, detail="That member has no access to this fund")
-    member = session.get(User, user_id)
-    if member is None or member.role != UserRole.investor:
-        raise HTTPException(status_code=400, detail="Only investor members can be marked exited")
+        # A manually-entered investor may have statements without an access grant yet
+        # (e.g. from the Capital Accounts screen). Marking them exited creates the roster
+        # row with the flag set; clearing an exit that doesn't exist stays a 404.
+        if body.exited_on is None:
+            raise HTTPException(status_code=404, detail="That member has no access to this fund")
+        access = EntityAccess(user_id=user_id, entity_id=entity_id)
+        session.add(access)
+        session.flush()
 
     access.exited_on = body.exited_on
     session.add(access)