Unbounded DAG pinning in Filecoin Pin can exhaust server resources

Filecoin Pin is an IPFS Pinning Service API implementation that pins to Filecoin's PDP service. In daemon deployments up to and including version 1.1.0, `POST /pins` in `src/filecoin-pinning-server.ts` checks a caller-supplied CID with `CID.parse` and passes it to `pinStore.pin`, but does not enforce request rate limits or per-user quotas. In `src/filecoin-pin-store.ts`, each pin independently schedules `_processPinInBackground` with `setTimeout` without a queue, semaphore or concurrency cap, then recursively traverses the full DAG using `helia.pins.add(cid)`. The per-pin Helia/Bitswap node in `src/create-pinning-helia.ts` has no application-level byte, block or traversal-time limits. Blocks are written under `carStoragePath` by `src/core/car/car-blockstore-base.ts` and `src/core/car/car-file-backend.ts`, with `stats.totalSize` updated only after writing. An authenticated caller, or an anonymous caller when `ALLOW_NO_AUTH=true`, can submit large DAGs and exhaust disk, network, CPU, memory and libp2p resources, causing service degradation or host/process failure and leaving partial CAR files requiring recovery. The default localhost binding and token requirement reduce exposure. Because nodes have no bootstrap or mDNS configuration, a CID alone may not be fetchable, but caller-supplied `origins` can point to a reachable attacker-controlled libp2p source; concurrent requests accelerate resource pressure. Version 1.1.1 documents operational mitigations but does not implement the missing resource controls.