Tell users where to go after the migration: filecoin-pin owns ongoing storage

### Description

ipfs2foc is a one-shot workflow: migrate already-pinned IPFS data onto Filecoin Onchain Cloud without re-chunking. Nothing tells users what to use after that migration lands. The README mentions [filecoin-pin](https://github.com/filecoin-project/filecoin-pin) only as a payment-setup prerequisite, the Scope and limits section covers technical caps, and neither `report` output nor the console completion screen points anywhere next.

The risk is users adopting ipfs2foc as their ongoing storage tool: filing feature requests for upload workflows this project deliberately does not own, or re-running a migration tool to store new data. Post-migration storage on FOC is filecoin-pin's job.

### Scope

1. README: an "After the migration" section stating that ipfs2foc's job ends when `report` reconciles, and that new data going to FOC belongs in filecoin-pin.
2. CLI: the `upload` and `report` completion summaries print the same pointer.
3. Console: the run-complete screen says it too.

One sentence of positioning, repeated at every exit point of the flow.

Start with the README, the CLI completion summaries for upload and report, and the console run-complete screen. Trace where each exit-point message is assembled, then add the same pointer to filecoin-pin and verify that the README explains the migration boundary and ongoing-storage ownership consistently.

Written by the indexing model from the issue text.