A claimed PC forgets the old login and the old cameras

Seen on the first claimed demo install: 'session expired' on every
screen, signed in as a user from the previous demo's head office, and
'Watching 3 cameras' for a shop with one - the PC had offered its two
leftover cameras up to head office, without their passwords, so the
same lens was listed twice and one copy could never be pushed anywhere.

Claiming now clears any stored session (a new head office is a new
world), a session whose refresh fails is forgotten on disk as well as
in memory so the app returns to Login by itself, and the demo setup
removes cameras left from an earlier install before it joins the shop,
because head office is the source of truth from then on.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KGcjxF1cNLcuwc3DAPcnfj

desktop/internal/cloud/client.go

@@ -108,8 +108,16 @@ func (c *Client) do(ctx context.Context, method, path string, body, out any) err
 	}
 	if rerr := c.Refresh(ctx); rerr != nil {
 		// The refresh token is gone too, so this really is a sign-in, not a
-		// transient failure. Report it as such so the UI shows the login sheet
-		// rather than an error dialog.
+		// transient failure. Forget the session - in memory AND on disk, through
+		// the same callback that persists rotations - so the app goes back to
+		// Login instead of showing "session expired" on every screen until
+		// somebody finds Sign out. Seen on a PC that had been claimed against a
+		// demo head office and then re-claimed against the real one: the old
+		// login sat there, dead, for the whole session.
+		c.Clear()
+		if c.onRefresh != nil {
+			c.onRefresh(Session{})
+		}
 		return ErrUnauthorized
 	}
 	return c.send(ctx, method, path, raw, out)