Explorer does not display service metadata on rail views

## Current behavior

[Filecoin Services documents `IFilecoinServiceMetadata`](https://github.com/FilOzone/filecoin-services/blob/c7ad4c5a700455a97f2f776d087ae23e9779511f/README.md#service-metadata) as the convention for exposing `name()`, `description()`, and `homepage()`. The README specifically recommends it so explorers and clients can identify FOC services without hard-coded address maps.

FCSS ValidatorBeacon v1.3.0 exposes the two fields needed for the service label:

- `name()` returns `FCSS`
- `description()` returns `Filecoin Cold Storage Service`

[Mainnet rail 2466](https://pay.filecoin.cloud/mainnet/rails/2466) uses one of these proxies. The detail page still shows raw operator and validator addresses, while rail tables show the raw operator address.

The current rail views resolve labels through `knownAddresses`. That works for a service with one stable address. FCSS creates a separate validator proxy per deal, so adding every proxy to that map would not scale.

This looks like a gap between the documented FOC metadata convention and the current Explorer rendering.

## Expected behavior

When an operator or validator contract implements `IFilecoinServiceMetadata`, the Explorer should show its service metadata wherever that contract is presented, including rail details and rail tables. The underlying address should remain available.

If the metadata cannot be read, the page should retain its current address-only rendering. FCSS is being updated on both maintained contract lines to implement the full interface, including `homepage()`.

Grouping multiple rails by service can remain a separate feature.

References:

- related metadata work for the Add Service flow: https://github.com/FilOzone/filecoin-pay-explorer/pull/366
- current rail detail rendering: https://github.com/FilOzone/filecoin-pay-explorer/blob/2b1001cb69fcca44afa41920c5f9705ba1de0eb2/apps/explorer/src/components/Rail/components/Stats.tsx#L239-L252
- current rail table operator column: https://github.com/FilOzone/filecoin-pay-explorer/blob/2b1001cb69fcca44afa41920c5f9705ba1de0eb2/apps/explorer/src/components/Rails/data/column-definitions.tsx#L53-L67
- current address labels: https://github.com/FilOzone/filecoin-pay-explorer/blob/2b1001cb69fcca44afa41920c5f9705ba1de0eb2/apps/explorer/src/constants/known-addresses.ts#L1-L20
- metadata interface: https://github.com/FilOzone/filecoin-services/blob/c7ad4c5a700455a97f2f776d087ae23e9779511f/service_contracts/src/IFilecoinServiceMetadata.sol
- FCSS background: https://github.com/FilOzone/filecoin-services/issues/535