Probe Starknet for its chain id

[haiyuechen-nearone]

Background

Part of #4003. First slice: introduces the probe machinery in foreign-chain-health-check (probe_all_providers, per provider status) with Starknet as the first covered chain, via starknet_chainId.

Acceptance Criteria

• A Starknet provider answering the expected chain id is reported healthy; a different chain id is reported unhealthy.
• Every configured provider gets its own status row; a chain without probing logic reports ProbeNotImplemented.
• No report row renders upstream error text, so credentials spliced into URLs cannot leak.

[haiyuechen-nearone]

Done in #4013.