CDN-217: The First Mode Opening

CDN-217 applies the CDN-216 provenance gate to the current TRAPPIST-1 timing coverage. CDN-214 gives external coverage for planets b, d, and e, which validates a forecast window but completes zero predeclared TTY modes. The first opening is therefore decided by public c or f timing. A c timing opens two modes, b-c-d and c-d-e; an f timing opens one mode, d-e-f, and it is the shortest-Laplace single-mode opener at 4847.318 days. No TTY candidate is paid now: any future c or f addition must still pass public timing, uncertainty, residual-test, no-fit-reuse, and provenance gates.